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|---|---|---|---|---|---|---|---|---|---|
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 82,841 | <pre><code>import os
os.path.exists(filename)
</code></pre>
| 85 | 2008-09-17T12:56:22Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 82,846 | <p>You have the <a href="https://docs.python.org/2/library/os.path.html#os.path.exists"><code>os.path.exists</code></a> function:</p>
<pre><code>import os.path
os.path.exists(file_path)
</code></pre>
<p>This returns <code>True</code> for both files and directories but you can additionally use <code>os.path.isfile</code> to test if it's a file specifically.</p>
| 964 | 2008-09-17T12:57:08Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 82,852 | <p>You can also use <a href="https://docs.python.org/2/library/os.path.html#os.path.isfile"><code>os.path.isfile</code></a></p>
<blockquote>
<p>Return <code>True</code> if path is an existing regular file. This follows symbolic links, so both <a href="https://docs.python.org/2/library/os.path.html#os.path.islink">islink()</a> and <a href="https://docs.python.org/2/library/os.path.html#os.path.isfile">isfile()</a> can be true for the same path.</p>
</blockquote>
<pre><code>import os.path
os.path.isfile(fname)
</code></pre>
<p>if you need to be sure it's a file.</p>
<p>Starting with Python 3.4, the <a href="https://docs.python.org/3/library/pathlib.html#pathlib.Path.is_file"><code>pathlib</code> module</a> offers an object-oriented approach:</p>
<pre><code>from pathlib import Path
my_file = Path("/path/to/file")
if my_file.is_file():
# file exists
</code></pre>
| 2,356 | 2008-09-17T12:57:51Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 83,012 | <p>Additionally, <code>os.access()</code>:</p>
<pre><code>if os.access("myfile", os.R_OK):
with open("myfile") as fp:
return fp.read()
</code></pre>
<p>Being <code>R_OK</code>, <code>W_OK</code>, and <code>X_OK</code> the flags to test for permissions (<a href="https://docs.python.org/3/library/os.html#os.access">doc</a>).</p>
| 18 | 2008-09-17T13:13:31Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 84,173 | <p>Unlike <a href="http://docs.python.org/3.3/library/os.path.html?highlight=os.path#os.path.isfile"><code>isfile()</code></a>, <a href="http://docs.python.org/3.3/library/os.path.html?highlight=os.path#os.path.exists"><code>exists()</code></a> will yield <em>True</em> for directories.<br>
So depending on if you want only plain files or also directories, you'll use <code>isfile()</code> or <code>exists()</code>. Here is a simple REPL output.</p>
<pre><code>>>> print os.path.isfile("/etc/password.txt")
True
>>> print os.path.isfile("/etc")
False
>>> print os.path.isfile("/does/not/exist")
False
>>> print os.path.exists("/etc/password.txt")
True
>>> print os.path.exists("/etc")
True
>>> print os.path.exists("/does/not/exist")
False
</code></pre>
| 640 | 2008-09-17T15:01:14Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 1,671,095 | <p>Prefer the try statement. It's considered better style and avoids race conditions.</p>
<p>Don't take my word for it. There's plenty of support for this theory. Here's a couple:</p>
<ul>
<li>Style: Section "Handling unusual conditions" of <a href="http://allendowney.com/sd/notes/notes11.txt">http://allendowney.com/sd/notes/notes11.txt</a></li>
<li><a href="https://developer.apple.com/library/mac/#documentation/security/conceptual/SecureCodingGuide/Articles/RaceConditions.html#//apple_ref/doc/uid/TP40002585-SW8">Avoiding Race Conditions</a></li>
</ul>
| 87 | 2009-11-04T00:48:06Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 4,247,590 | <p>Just to add to the confusion, it seems that the try: open() approach suggested above doesn't work in Python, as file access isn't exclusive, not even when writing to files, c.f. <a href="http://stackoverflow.com/questions/186202/what-is-the-best-way-to-open-a-file-for-exclusive-access-in-python">What is the best way to open a file for exclusive access in Python?</a>.</p>
| 16 | 2010-11-22T16:19:19Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 4,799,818 | <p>You could try this: (safer)</p>
<pre><code>try:
# http://effbot.org/zone/python-with-statement.htm
# with is more safe to open file
with open('whatever.txt') as fh:
# do something with fh
except IOError as e:
print("({})".format(e))
</code></pre>
<p>the ouput would be:</p>
<blockquote>
<p>([Errno 2] No such file or directory:
'whatever.txt')</p>
</blockquote>
<p>then, depending on the result, your program can just keep running from there or you can code to stop it if you want.</p>
| 33 | 2011-01-25T23:00:01Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 7,201,731 | <pre><code>import os
path = /path/to/dir
root,dirs,files = os.walk(path).next()
if myfile in files:
print "yes it exists"
</code></pre>
<p>This is helpful when checking for several files. Or you want to do a set intersection/ subtraction with an existing list.</p>
| 6 | 2011-08-26T08:08:04Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 8,876,254 | <p>Use <a href="https://docs.python.org/3.3/library/os.path.html?highlight=os.path#os.path.isfile"><code>os.path.isfile()</code></a> with <a href="https://docs.python.org/3.3/library/os.html?highlight=os.access#os.access"><code>os.access()</code></a>:</p>
<pre><code>import os
import os.path
PATH='./file.txt'
if os.path.isfile(PATH) and os.access(PATH, os.R_OK):
print "File exists and is readable"
else:
print "Either file is missing or is not readable"
</code></pre>
| 156 | 2012-01-16T05:57:12Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 11,267,256 | <p>This sample function will test for a file's presence in a very Pythonic way using try .. except:</p>
<pre><code>def file_exists(filename):
try:
with open(filename) as f:
return True
except IOError:
return False
</code></pre>
| -2 | 2012-06-29T18:40:31Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 15,432,665 | <p>You can simply use tempfile module to know whether file exists or not:</p>
<pre><code>import tempfile
tempfile._exists('filename') # return True or False
</code></pre>
| -3 | 2013-03-15T12:36:34Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 15,818,776 | <p>You should definitely use this one.</p>
<pre><code>from os.path import exists
if exists("file") == True:
print "File exists."
elif exists("file") == False:
print "File doesn't exist."
</code></pre>
| 4 | 2013-04-04T18:21:11Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 17,344,732 | <p>This is the simplest way to check if a file exists. Just <strong>because</strong> the file existed when you checked doesn't <strong>guarantee</strong> that it will be there when you need to open it.</p>
<pre><code>import os
fname = "foo.txt"
if os.path.isfile(fname):
print "file does exist at this time"
else:
print "no such file"
</code></pre>
| 78 | 2013-06-27T13:38:04Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 18,994,918 | <p>It doesn't seem like there's a meaningful functional difference between try/except and <code>isfile()</code>, so you should use which one makes sense.</p>
<p>If you want to read a file, if it exists, do</p>
<pre><code>try:
f = open(filepath)
except IOError:
print 'Oh dear.'
</code></pre>
<p>But if you just wanted to rename a file if it exists, and therefore don't need to open it, do</p>
<pre><code>if os.path.isfile(filepath):
os.rename(filepath, filepath + '.old')
</code></pre>
<p>If you want to write to a file, if it doesn't exist, do</p>
<pre><code># python 2
if not os.path.isfile(filepath):
f = open(filepath, 'w')
# python 3, x opens for exclusive creation, failing if the file already exists
try:
f = open(filepath, 'wx')
except IOError:
print 'file already exists'
</code></pre>
<p>If you need file locking, that's a different matter.</p>
| 44 | 2013-09-25T01:52:46Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 20,005,069 | <p>If you want to do what in bash would be</p>
<pre><code>if [ -e '$FILE' ]; then
prog '$FILE'
fi
</code></pre>
<p>which I sometimes do when using Python to do more complicated manipulation of a list of names (as I sometimes need to use Python for), the try open(file): except: method isn't really what's wanted, as it is not the Python process that is intended to open the file. In one case, the purpose is to filter a list of names according to whether they exist at present (and there are no processes likely to delete the file, nor security issues since this is on my Raspberry Pi which has no sensitive files on its SD).</p>
<p>I'm wondering whether a 'Simple Patterns' site would be a good idea? So that, for example, you could illustrate both methods with links between them and links to discussions as to when to use which pattern.</p>
| 2 | 2013-11-15T15:52:22Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 21,641,213 | <p><strong>Python 3.4</strong> has an object-oriented path module: <a href="http://docs.python.org/3.4/library/pathlib.html"><strong>pathlib</strong></a>. Using this new module, you can check whether a file exists like this:</p>
<pre><code>import pathlib
p = pathlib.Path('path/to/file')
if p.is_file(): # or p.is_dir() to see if it is a directory
# do stuff
</code></pre>
<p>You can (and usually should) still use a <code>try/except</code> block when opening files:</p>
<pre><code>try:
with p.open() as f:
# do awesome stuff
except OSError:
print('Well darn.')
</code></pre>
<p>The pathlib module has lots of cool stuff in it: convenient globbing, checking file's owner, easier path joining, etc. It's worth checking out. If you're on an older Python (version 2.6 or later), you can still install pathlib with pip:</p>
<pre><code># installs pathlib on older Python versions
pip install pathlib
</code></pre>
| 65 | 2014-02-08T02:38:42Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 21,688,350 | <p>You can write Brian's suggestion without the <code>try:</code>.</p>
<pre><code>from contextlib import suppress
with suppress(IOError), open('filename'):
process()
</code></pre>
<p><code>supress</code> is part of Python 3.4. In older releases you can quickly write your own supress:</p>
<pre><code>from contextlib import contextmanager
@contextmanager
def suppress(*exceptions):
try:
yield
except exceptions:
pass
</code></pre>
| 9 | 2014-02-10T21:30:20Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 23,826,292 | <p>You can use following open method to check if file exists + readable</p>
<pre><code>open(inputFile, 'r')
</code></pre>
| 7 | 2014-05-23T10:01:20Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 26,335,110 | <p>If the file is for opening you could use one of the following techniques:</p>
<pre><code>>>> with open('somefile', 'xt') as f: #Using the x-flag, Python3.3 and above
... f.write('Hello\n')
>>> if not os.path.exists('somefile'):
... with open('somefile', 'wt') as f:
... f.write("Hello\n")
... else:
... print('File already exists!')
</code></pre>
| 4 | 2014-10-13T07:45:16Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 26,433,646 | <p>To check if a file exists, </p>
<pre><code>from sys import argv
from os.path import exists
script, filename = argv
target = open(filename)
print "file exists: %r" % exists(filename)
</code></pre>
| 7 | 2014-10-17T21:25:30Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 27,581,592 | <p>You can use the "OS" library of python.</p>
<pre><code>>>> import os
>>> os.path.exists("C:\\Users\\####\\Desktop\\test.txt")
True
>>> os.path.exists("C:\\Users\\####\\Desktop\\test.tx")
False
</code></pre>
| 7 | 2014-12-20T15:21:40Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 27,661,444 | <p>Although I always recommend using <code>try</code> and <code>except</code> statements, here's a few possibilities for you (My personal favourite is using <code>os.access</code>:</p>
<ol>
<li><p>Try opening the file:</p>
<p>Opening the file will always verify the existence of the file. You can make a function just like so:</p>
<pre><code>def File_Existence(filepath):
f = open(filepath)
return True
</code></pre>
<p>If it's False, it will stop execution with an unhanded IOError
or OSError in later versions of python. To catch the exception,
you have to use a try except clause. Of course, you can always use a <code>try</code> <code>except</code> statement like so (Thanks to <a href="http://stackoverflow.com/users/3256073/hsandt">hsandt</a> for making me think):</p>
<pre><code>def File_Existence(filepath):
try:
f = open(filepath)
except IOError, OSError: # Note OSError is for later versions of python
return False
return True
</code></pre></li>
<li><p>Use <code>os.path.exists(path)</code>:</p>
<p>This will check the existence of what you specify. However, it checks for files <em>and</em> directories so beware about how you use it.</p>
<pre><code>import os.path
>>> os.path.exists("this/is/a/directory")
True
>>> os.path.exists("this/is/a/file.txt")
True
>>> os.path.exists("not/a/directory")
False
</code></pre></li>
<li><p>Use <code>os.access(path, mode)</code>:</p>
<p>This will check whether you have access to the file. It will check for permissions. Based on the os.py documentation, typing in <code>os.F_OK</code>, will check the existence of the path. However, using this will create a security hole, as someone can attack your file using the time between checking the permissions and opening the file. You should instead go directly to opening the file instead of checking its permissions. (<a href="https://docs.python.org/2/glossary.html#term-eafp">EAFP</a> vs <a href="https://docs.python.org/2/glossary.html#term-lbyl">LBYP</a>). If you're not going to open the file afterwards, and only checking its existence, then you can use this.</p>
<p>Anyways, here:</p>
<pre><code>>>> import os
>>> os.access("/is/a/file.txt", os.F_OK)
True
</code></pre></li>
</ol>
<p>I should also mention that there are two ways that you will not be able to verify the existence of a file. Either the issue will be <code>permission denied</code> or <code>no such file or directory</code>. If you catch an <code>IOError</code>, set the <code>IOError as e</code> (Like my first option), and then type in <code>print(e.args)</code> so that you can hopefully determine your issue. Hope it helps! :)</p>
| 25 | 2014-12-26T20:05:32Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 29,909,391 | <pre><code>if os.path.isfile(path_to_file):
try:
open(path_to_file)
pass
except IOError as e:
print "Unable to open file"
</code></pre>
<blockquote>
<p>Raising exceptions is considered to be an acceptable, and Pythonic,
approach for flow control in your program. Consider handling missing
files with IOErrors. In this situation, an IOError exception will be
raised if the file exists but the user does not have read permissions.</p>
</blockquote>
<p>SRC: <a href="http://www.pfinn.net/python-check-if-file-exists.html">http://www.pfinn.net/python-check-if-file-exists.html</a></p>
| 15 | 2015-04-28T02:45:31Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 30,444,116 | <pre><code>import os
#Your path here e.g. "C:\Program Files\text.txt"
if os.path.exists("C:\..."):
print "File found!"
else:
print "File not found!"
</code></pre>
<p>Importing <code>os</code> makes it easier to navigate and perform standard actions with your operating system. </p>
<p>For reference also see <a href="/q/82831">How to check whether a file exists using Python?</a></p>
<p>If you need high-level operations, use <code>shutil</code>.</p>
| 53 | 2015-05-25T18:29:22Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 31,824,912 | <pre><code>import os.path
def isReadableFile(file_path, file_name):
full_path = file_path + "/" + file_name
try:
if not os.path.exists(file_path):
print "File path is invalid."
return False
elif not os.path.isfile(full_path):
print "File does not exist."
return False
elif not os.access(full_path, os.R_OK):
print "File cannot be read."
return False
else:
print "File can be read."
return True
except IOError as ex:
print "I/O error({0}): {1}".format(ex.errno, ex.strerror)
except Error as ex:
print "Error({0}): {1}".format(ex.errno, ex.strerror)
return False
#------------------------------------------------------
path = "/usr/khaled/documents/puzzles"
fileName = "puzzle_1.txt"
isReadableFile(path, fileName)
</code></pre>
| 5 | 2015-08-05T06:28:27Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 31,932,925 | <blockquote>
<h1>How do I check whether a file exists, using Python, without using a try statement?</h1>
</blockquote>
<h2>Recommendations:</h2>
<p><strong>suppress</strong></p>
<p>Python 3.4 gives us the <a href="https://docs.python.org/3/library/contextlib.html#contextlib.suppress"><code>suppress</code></a> context manager (previously the <a href="https://bugs.python.org/issue19266"><code>ignore</code></a> context manager), which does semantically exactly the same thing in fewer lines, while also (at least superficially) meeting the original ask to avoid a <code>try</code> statement:</p>
<pre><code>from contextlib import suppress
with suppress(OSError), open(path) as f:
f.read()
</code></pre>
<p>Usage:</p>
<pre><code>>>> with suppress(OSError), open('doesnotexist') as f:
... f.read()
...
>>>
</code></pre>
<p>For earlier Pythons, you could roll your own <code>suppress</code>, but without a <code>try</code> will be much more verbose than with. I do believe <strong>this actually is the only answer that doesn't use <code>try</code> at any level</strong> that can be applied to prior to Python 3.4 because it uses a context manager instead:</p>
<pre><code>class suppress(object):
def __init__(self, *exceptions):
self.exceptions = exceptions
def __enter__(self):
return self
def __exit__(self, exc_type, exc_value, traceback):
if exc_type is not None:
return issubclass(exc_type, self.exceptions)
</code></pre>
<p>Easier with a try:</p>
<pre><code>from contextlib import contextmanager
@contextmanager
def suppress(*exceptions):
try:
yield
except exceptions:
pass
</code></pre>
<h2>Other, possibly problematic, options:</h2>
<p><strong>isfile</strong></p>
<pre><code>import os
os.path.isfile(path)
</code></pre>
<p>from the <a href="https://docs.python.org/library/os.path.html#os.path.isfile">docs</a>:</p>
<blockquote>
<p><code>os.path.isfile(path)</code></p>
<p>Return True if path is an existing regular file. This follows symbolic
links, so both <code>islink()</code> and <code>isfile()</code> can be true for the same path.</p>
</blockquote>
<p>But if you examine the <a href="https://hg.python.org/cpython/file/tip/Lib/genericpath.py#l25">source</a> of this function, you'll see it actually does use a try statement:</p>
<blockquote>
<pre><code># This follows symbolic links, so both islink() and isdir() can be true
# for the same path on systems that support symlinks
def isfile(path):
"""Test whether a path is a regular file"""
try:
st = os.stat(path)
except os.error:
return False
return stat.S_ISREG(st.st_mode)
</code></pre>
</blockquote>
<pre><code>>>> OSError is os.error
True
</code></pre>
<p>All it's doing is using the given path to see if it can get stats on it, catching <code>OSError</code> and then checking if it's a file if it didn't raise the exception.</p>
<p>If you intend to do something with the file, I would suggest directly attempting it with a try-except to avoid a race condition:</p>
<pre><code>try:
with open(path) as f:
f.read()
except OSError:
pass
</code></pre>
<p><strong>os.access</strong></p>
<p>Available for Unix and Windows is <code>os.access</code>, but to use you must pass flags, and it does not differentiate between files and directories. This is more used to test if the real invoking user has access in an elevated privilege environment:</p>
<pre><code>import os
os.access(path, os.F_OK)
</code></pre>
<p>It also suffers from the same race condition problems as <code>isfile</code>. From the <a href="https://docs.python.org/2/library/os.html#os.access">docs</a>:</p>
<blockquote>
<p>Note:
Using access() to check if a user is authorized to e.g. open a file
before actually doing so using open() creates a security hole, because
the user might exploit the short time interval between checking and
opening the file to manipulate it. Itâs preferable to use EAFP
techniques. For example:</p>
<pre><code>if os.access("myfile", os.R_OK):
with open("myfile") as fp:
return fp.read()
return "some default data"
</code></pre>
<p>is better written as:</p>
<pre><code>try:
fp = open("myfile")
except IOError as e:
if e.errno == errno.EACCES:
return "some default data"
# Not a permission error.
raise
else:
with fp:
return fp.read()
</code></pre>
</blockquote>
| 33 | 2015-08-11T03:54:25Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 32,288,118 | <p>Here's a 1 line Python command for the Linux command line environment. I find this VERY HANDY since I'm not such a hot Bash guy.</p>
<pre><code>python -c "import os.path; print os.path.isfile('/path_to/file.xxx')"
</code></pre>
<p>I hope this is helpful.</p>
| 11 | 2015-08-29T16:15:29Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 33,554,911 | <p>In <code>Python 3.4</code> the language provides a new module to manage files:</p>
<pre><code>import pathlib
path = pathlib.Path('path/to/file')
if path.is_file(): # if you want to check a directory: path.is_dir()
# if it is true, return true on your code
</code></pre>
| 15 | 2015-11-05T21:15:03Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 34,295,323 | <p><strong>Demo</strong>: </p>
<pre><code>try:
with open('my_settings.dat') as fp:
pass
except IOError as e:
print "Unable to open file" #Does not exist OR no read permissions
</code></pre>
<p>Handling missing files with IOErrors rather than if statements.An IOError exception will be raised if the file exists but the user does not have read permissions.</p>
| 1 | 2015-12-15T17:10:49Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 35,602,588 | <p>In 2016 the best way is still using <code>os.path.isfile</code></p>
<pre><code>>>> os.path.isfile('/path/to/some/file.txt')
</code></pre>
<p>Or in <code>python3</code> you can use <code>pathlib</code></p>
<pre><code>import pathlib
path = pathlib.Path('/path/to/some/file.txt')
if path.is_file():
...
</code></pre>
| 24 | 2016-02-24T12:44:10Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 36,882,475 | <pre><code>import os
iffile = os.system('ls filename') ##### returns 0 if success
if iffile == 0:
print 'file exists'
else:
print 'file does not exist'
</code></pre>
| 1 | 2016-04-27T06:54:11Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 37,050,053 | <p>I'm the author of a package that's been around for about 10 years, and it has a function that addresses this question directly. Basically, if you are on a non-windows system, it uses <code>Popen</code> to access <code>find</code>. However, if you are on windows, it replicates <code>find</code> with an efficient filesystem walker. The code itself does not use a <code>try</code> block⦠except in determining the operating system and thus steering you to the "unix"-style <code>find</code> or the hand-buillt <code>find</code>. Timing tests showed that the <code>try</code> was faster in determining the OS, so I did use one there (but nowhere else).</p>
<pre><code>>>> import pox
>>> pox.find('*python*', type='file', root=pox.homedir(), recurse=False)
['/Users/mmckerns/.python']
</code></pre>
<p>And the docâ¦</p>
<pre><code>>>> print pox.find.__doc__
find(patterns[,root,recurse,type]); Get path to a file or directory
patterns: name or partial name string of items to search for
root: path string of top-level directory to search
recurse: if True, recurse down from root directory
type: item filter; one of {None, file, dir, link, socket, block, char}
verbose: if True, be a little verbose about the search
On some OS, recursion can be specified by recursion depth (an integer).
patterns can be specified with basic pattern matching. Additionally,
multiple patterns can be specified by splitting patterns with a ';'
For example:
>>> find('pox*', root='..')
['/Users/foo/pox/pox', '/Users/foo/pox/scripts/pox_launcher.py']
>>> find('*shutils*;*init*')
['/Users/foo/pox/pox/shutils.py', '/Users/foo/pox/pox/__init__.py']
>>>
</code></pre>
<p>The implementation, if you care to look, is here:
<a href="https://github.com/uqfoundation/pox/blob/89f90fb308f285ca7a62eabe2c38acb87e89dad9/pox/shutils.py#L190">https://github.com/uqfoundation/pox/blob/89f90fb308f285ca7a62eabe2c38acb87e89dad9/pox/shutils.py#L190</a></p>
| 5 | 2016-05-05T12:00:42Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 37,702,905 | <p>You can use os.listdir to check if a file is in a certain directory.</p>
<pre><code>import os
if 'file.ext' in os.listdir('dirpath'):
#code
</code></pre>
| 2 | 2016-06-08T12:45:32Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 38,793,323 | <p>Adding one more slight variation which isn't exactly reflected in the other answers.</p>
<p>This will handle the case of the <code>file_path</code> being <code>None</code> or empty string.</p>
<p></p>
<pre><code>def file_exists(file_path):
if not file_path:
return False
elif not os.path.isfile(file_path):
return False
else:
return True
</code></pre>
| 2 | 2016-08-05T15:54:37Z | [
"python",
"file",
"filesystems"
] |
How do I check whether a file exists using Python? | 82,831 | <p>How do I check whether a file exists, without using the <a href="https://docs.python.org/3.6/reference/compound_stmts.html#try"><code>try</code></a> statement?</p>
| 2,729 | 2008-09-17T12:55:00Z | 39,932,496 | <p>Testing for files and folders with <code>os.path.isfile()</code>, <code>os.path.isdir()</code> and <code>os.path.exists()</code></p>
<p>Assuming that the "path" is a valid path, this table shows what is returned by each function for files and folders:</p>
<p><a href="http://i.stack.imgur.com/tOs9p.png"><img src="http://i.stack.imgur.com/tOs9p.png" alt="enter image description here"></a></p>
<p>You can also test if a file is a certain type of file using <code>os.path.splitext()</code> to get the extension (if you don't already know it)</p>
<pre><code>>>> import os
>>> path = "path to a word document"
>>> os.path.isfile(path)
True
>>> os.path.splitext(path)[1] == ".docx" # test if the extension is .docx
True
</code></pre>
| 6 | 2016-10-08T12:43:02Z | [
"python",
"file",
"filesystems"
] |
How to programmatically enable/disable network interfaces? (Windows XP) | 83,756 | <p>I need to enable/disable completely network interfaces from a script in Windows XP. I'm looking for a python solution, but any general way (eg WMI, some command-line à la netsh, some windows call) is welcome and will be adjusted. Thanks.</p>
| 11 | 2008-09-17T14:22:56Z | 83,800 | <p>The <a href="http://support.microsoft.com/kb/311272" rel="nofollow">devcon</a> tool can control the NIC, but not the interface directly. It's a command-line version of the Device Manager applet.</p>
<pre><code>devcon disable (id or portion of name)
devcon enable (id or portion of name)
</code></pre>
| 0 | 2008-09-17T14:26:31Z | [
"python",
"networking",
"windows-xp"
] |
How to programmatically enable/disable network interfaces? (Windows XP) | 83,756 | <p>I need to enable/disable completely network interfaces from a script in Windows XP. I'm looking for a python solution, but any general way (eg WMI, some command-line à la netsh, some windows call) is welcome and will be adjusted. Thanks.</p>
| 11 | 2008-09-17T14:22:56Z | 83,890 | <p>this is VB.Net</p>
<pre><code>Dim objectQuery As New ObjectQuery("SELECT * FROM Win32_NetworkAdapter WHERE NetConnectionId IS NOT NULL")
Dim searcher As New ManagementObjectSearcher(scope, objectQuery)
Dim os As ManagementObject
Dim moColl As ManagementObjectCollection = searcher.Get()
Dim _list As String = ""
For Each os In moColl
Console.WriteLine(os("NetConnectionId"))
Next os
</code></pre>
<p>That will get all the interfaces on you computer. Then you can do netsh to disable it.</p>
<blockquote>
<p>netsh interface set interface
DISABLED</p>
</blockquote>
| 0 | 2008-09-17T14:35:20Z | [
"python",
"networking",
"windows-xp"
] |
How to programmatically enable/disable network interfaces? (Windows XP) | 83,756 | <p>I need to enable/disable completely network interfaces from a script in Windows XP. I'm looking for a python solution, but any general way (eg WMI, some command-line à la netsh, some windows call) is welcome and will be adjusted. Thanks.</p>
| 11 | 2008-09-17T14:22:56Z | 83,954 | <p>I can't seem to find any basic API for controlling interfaces on MSDN, apart from the RAS API's, but I don't think they apply to non-dialup connections. As you suggest yourself, netsh might be an option, supposedly it also has a programmatic interface: <a href="http://msdn.microsoft.com/en-us/library/ms708353(VS.85).aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/ms708353(VS.85).aspx</a></p>
<p>If you want to be pure Python, you can perhaps open a set of pipes to communicate with an netsh process.</p>
| 1 | 2008-09-17T14:40:45Z | [
"python",
"networking",
"windows-xp"
] |
How to programmatically enable/disable network interfaces? (Windows XP) | 83,756 | <p>I need to enable/disable completely network interfaces from a script in Windows XP. I'm looking for a python solution, but any general way (eg WMI, some command-line à la netsh, some windows call) is welcome and will be adjusted. Thanks.</p>
| 11 | 2008-09-17T14:22:56Z | 84,073 | <p>You may need to use WMI. This may serve as a good starting point:
<a href="http://msdn.microsoft.com/en-us/library/aa394595.aspx" rel="nofollow">http://msdn.microsoft.com/en-us/library/aa394595.aspx</a></p>
| 0 | 2008-09-17T14:52:35Z | [
"python",
"networking",
"windows-xp"
] |
How to programmatically enable/disable network interfaces? (Windows XP) | 83,756 | <p>I need to enable/disable completely network interfaces from a script in Windows XP. I'm looking for a python solution, but any general way (eg WMI, some command-line à la netsh, some windows call) is welcome and will be adjusted. Thanks.</p>
| 11 | 2008-09-17T14:22:56Z | 84,315 | <p>So far I've found the following Python solution:</p>
<pre><code>>>> import wmi; c=wmi.WMI()
>>> o=c.query("select * from Win32_NetworkAdapter where NetConnectionID='wifi'")[0]
>>> o.EnableDevice(1)
(-2147217407,)
</code></pre>
<p>which is translated, AFAIU, to the generic WMI error 0x80041001. Could be permissions.</p>
| 5 | 2008-09-17T15:14:44Z | [
"python",
"networking",
"windows-xp"
] |
How to programmatically enable/disable network interfaces? (Windows XP) | 83,756 | <p>I need to enable/disable completely network interfaces from a script in Windows XP. I'm looking for a python solution, but any general way (eg WMI, some command-line à la netsh, some windows call) is welcome and will be adjusted. Thanks.</p>
| 11 | 2008-09-17T14:22:56Z | 86,611 | <p>Using the netsh interface
Usage set interface [name = ] IfName
[ [admin = ] ENABLED|DISABLED
[connect = ] CONNECTED|DISCONNECTED
[newname = ] NewName ]</p>
<p>Try including everything inside the outer brackets:
netsh interface set interface name="thename" admin=disabled connect=DISCONNECTED newname="thename"</p>
<p>See also this MS KB page: <a href="http://support.microsoft.com/kb/262265/">http://support.microsoft.com/kb/262265/</a>
You could follow either of their suggestions.
For disabling the adapter, you will need to determine a way to reference the hardware device. If there will not be multiple adapters with the same name on the computer, you could possibly go off of the Description for the interface (or PCI ID works well). After that, using devcon (disable|enable). Devcon is an add-on console interface for the Device Manager.</p>
| 9 | 2008-09-17T19:20:31Z | [
"python",
"networking",
"windows-xp"
] |
How to programmatically enable/disable network interfaces? (Windows XP) | 83,756 | <p>I need to enable/disable completely network interfaces from a script in Windows XP. I'm looking for a python solution, but any general way (eg WMI, some command-line à la netsh, some windows call) is welcome and will be adjusted. Thanks.</p>
| 11 | 2008-09-17T14:22:56Z | 4,317,191 | <p>I found this .VBS script on the internet. It has the cool advantage of actually working on machines where I cannot get NETSH to work for this purpose.</p>
<pre><code>Const ssfCONTROLS = 3
sConnectionName = "Local Area Connection"
sEnableVerb = "En&able"
sDisableVerb = "Disa&ble"
set shellApp = createobject("shell.application")
set oControlPanel = shellApp.Namespace(ssfCONTROLS)
set oNetConnections = nothing
for each folderitem in oControlPanel.items
if folderitem.name = "Network Connections" then
set oNetConnections = folderitem.getfolder: exit for
end if
next
if oNetConnections is nothing then
msgbox "Couldn't find 'Network Connections' folder"
wscript.quit
end if
set oLanConnection = nothing
for each folderitem in oNetConnections.items
if lcase(folderitem.name) = lcase(sConnectionName) then
set oLanConnection = folderitem: exit for
end if
next
if oLanConnection is nothing then
msgbox "Couldn't find '" & sConnectionName & "' item"
wscript.quit
end if
bEnabled = true
set oEnableVerb = nothing
set oDisableVerb = nothing
s = "Verbs: " & vbcrlf
for each verb in oLanConnection.verbs
s = s & vbcrlf & verb.name
if verb.name = sEnableVerb then
set oEnableVerb = verb
bEnabled = false
end if
if verb.name = sDisableVerb then
set oDisableVerb = verb
end if
next
'debugging displays left just in case...
'
'msgbox s ': wscript.quit
'msgbox "Enabled: " & bEnabled ': wscript.quit
'not sure why, but invokeverb always seemed to work
'for enable but not disable.
'
'saving a reference to the appropriate verb object
'and calling the DoIt method always seems to work.
'
if bEnabled then
' oLanConnection.invokeverb sDisableVerb
oDisableVerb.DoIt
else
' oLanConnection.invokeverb sEnableVerb
oEnableVerb.DoIt
end if
'adjust the sleep duration below as needed...
'
'if you let the oLanConnection go out of scope
'and be destroyed too soon, the action of the verb
'may not take...
'
wscript.sleep 1000
</code></pre>
| 2 | 2010-11-30T18:34:44Z | [
"python",
"networking",
"windows-xp"
] |
Why isn't the 'len' function inherited by dictionaries and lists in Python | 83,983 | <p>example:</p>
<pre><code>a_list = [1, 2, 3]
a_list.len() # doesn't work
len(a_list) # works
</code></pre>
<p>Python being (very) object oriented, I don't understand why the 'len' function isn't inherited by the object.
Plus I keep trying the wrong solution since it appears as the logical one to me</p>
| 18 | 2008-09-17T14:43:18Z | 84,016 | <p>Maybe you're looking for <code>__len__</code>. If that method exists, then len(a) calls it:</p>
<pre><code>>>> class Spam:
... def __len__(self): return 3
...
>>> s = Spam()
>>> len(s)
3
</code></pre>
| 2 | 2008-09-17T14:46:43Z | [
"python"
] |
Why isn't the 'len' function inherited by dictionaries and lists in Python | 83,983 | <p>example:</p>
<pre><code>a_list = [1, 2, 3]
a_list.len() # doesn't work
len(a_list) # works
</code></pre>
<p>Python being (very) object oriented, I don't understand why the 'len' function isn't inherited by the object.
Plus I keep trying the wrong solution since it appears as the logical one to me</p>
| 18 | 2008-09-17T14:43:18Z | 84,019 | <p>It just isn't.</p>
<p>You can, however, do:</p>
<pre><code>>>> [1,2,3].__len__()
3
</code></pre>
<p>Adding a <code>__len__()</code> method to a class is what makes the <code>len()</code> magic work.</p>
| 10 | 2008-09-17T14:46:56Z | [
"python"
] |
Why isn't the 'len' function inherited by dictionaries and lists in Python | 83,983 | <p>example:</p>
<pre><code>a_list = [1, 2, 3]
a_list.len() # doesn't work
len(a_list) # works
</code></pre>
<p>Python being (very) object oriented, I don't understand why the 'len' function isn't inherited by the object.
Plus I keep trying the wrong solution since it appears as the logical one to me</p>
| 18 | 2008-09-17T14:43:18Z | 84,038 | <p>Well, there actually is a length method, it is just hidden:</p>
<pre><code>>>> a_list = [1, 2, 3]
>>> a_list.__len__()
3
</code></pre>
<p>The len() built-in function appears to be simply a wrapper for a call to the hidden <strong>len</strong>() method of the object.</p>
<p>Not sure why they made the decision to implement things this way though.</p>
| 2 | 2008-09-17T14:48:37Z | [
"python"
] |
Why isn't the 'len' function inherited by dictionaries and lists in Python | 83,983 | <p>example:</p>
<pre><code>a_list = [1, 2, 3]
a_list.len() # doesn't work
len(a_list) # works
</code></pre>
<p>Python being (very) object oriented, I don't understand why the 'len' function isn't inherited by the object.
Plus I keep trying the wrong solution since it appears as the logical one to me</p>
| 18 | 2008-09-17T14:43:18Z | 84,154 | <p>Guido's explanation is <a href="http://mail.python.org/pipermail/python-3000/2006-November/004643.html">here</a>:</p>
<blockquote>
<p>First of all, I chose len(x) over x.len() for HCI reasons (def __len__() came much later). There are two intertwined reasons actually, both HCI:</p>
<p>(a) For some operations, prefix notation just reads better than postfix â prefix (and infix!) operations have a long tradition in mathematics which likes notations where the visuals help the mathematician thinking about a problem. Compare the easy with which we rewrite a formula like x*(a+b) into x*a + x*b to the clumsiness of doing the same thing using a raw OO notation.</p>
<p>(b) When I read code that says len(x) I know that it is asking for the length of something. This tells me two things: the result is an integer, and the argument is some kind of container. To the contrary, when I read x.len(), I have to already know that x is some kind of container implementing an interface or inheriting from a class that has a standard len(). Witness the confusion we occasionally have when a class that is not implementing a mapping has a get() or keys() method, or something that isnât a file has a write() method.</p>
<p>Saying the same thing in another way, I see âlenâ as a built-in operation. Iâd hate to lose that. /â¦/</p>
</blockquote>
| 39 | 2008-09-17T14:59:53Z | [
"python"
] |
Why isn't the 'len' function inherited by dictionaries and lists in Python | 83,983 | <p>example:</p>
<pre><code>a_list = [1, 2, 3]
a_list.len() # doesn't work
len(a_list) # works
</code></pre>
<p>Python being (very) object oriented, I don't understand why the 'len' function isn't inherited by the object.
Plus I keep trying the wrong solution since it appears as the logical one to me</p>
| 18 | 2008-09-17T14:43:18Z | 84,155 | <p>The short answer: 1) backwards compatibility and 2) there's not enough of a difference for it to really matter. For a more detailed explanation, read on.</p>
<p>The idiomatic Python approach to such operations is special methods which aren't intended to be called directly. For example, to make <code>x + y</code> work for your own class, you write a <code>__add__</code> method. To make sure that <code>int(spam)</code> properly converts your custom class, write a <code>__int__</code> method. To make sure that <code>len(foo)</code> does something sensible, write a <code>__len__</code> method.</p>
<p>This is how things have always been with Python, and I think it makes a lot of sense for some things. In particular, this seems like a sensible way to implement operator overloading. As for the rest, different languages disagree; in Ruby you'd convert something to an integer by calling <code>spam.to_i</code> directly instead of saying <code>int(spam)</code>.</p>
<p>You're right that Python is an extremely object-oriented language and that having to call an external function on an object to get its length seems odd. On the other hand, <code>len(silly_walks)</code> isn't any more onerous than <code>silly_walks.len()</code>, and Guido has said that he actually prefers it (<a href="http://mail.python.org/pipermail/python-3000/2006-November/004643.html">http://mail.python.org/pipermail/python-3000/2006-November/004643.html</a>).</p>
| 11 | 2008-09-17T14:59:54Z | [
"python"
] |
Why isn't the 'len' function inherited by dictionaries and lists in Python | 83,983 | <p>example:</p>
<pre><code>a_list = [1, 2, 3]
a_list.len() # doesn't work
len(a_list) # works
</code></pre>
<p>Python being (very) object oriented, I don't understand why the 'len' function isn't inherited by the object.
Plus I keep trying the wrong solution since it appears as the logical one to me</p>
| 18 | 2008-09-17T14:43:18Z | 84,205 | <p>This way fits in better with the rest of the language. The convention in python is that you add <code>__foo__</code> special methods to objects to make them have certain capabilities (rather than e.g. deriving from a specific base class). For example, an object is </p>
<ul>
<li>callable if it has a <code>__call__</code> method </li>
<li>iterable if it has an <code>__iter__</code> method, </li>
<li>supports access with [] if it has <code>__getitem__</code> and <code>__setitem__</code>. </li>
<li>...</li>
</ul>
<p>One of these special methods is <code>__len__</code> which makes it have a length accessible with <code>len()</code>.</p>
| 4 | 2008-09-17T15:04:16Z | [
"python"
] |
Why isn't the 'len' function inherited by dictionaries and lists in Python | 83,983 | <p>example:</p>
<pre><code>a_list = [1, 2, 3]
a_list.len() # doesn't work
len(a_list) # works
</code></pre>
<p>Python being (very) object oriented, I don't understand why the 'len' function isn't inherited by the object.
Plus I keep trying the wrong solution since it appears as the logical one to me</p>
| 18 | 2008-09-17T14:43:18Z | 84,337 | <p>there is some good info below on why certain things are functions and other are methods. It does indeed cause some inconsistencies in the language.</p>
<p><a href="http://mail.python.org/pipermail/python-dev/2008-January/076612.html" rel="nofollow">http://mail.python.org/pipermail/python-dev/2008-January/076612.html</a></p>
| 2 | 2008-09-17T15:16:26Z | [
"python"
] |
Running multiple sites from a single Python web framework | 85,119 | <p>What are come good (or at least clever) ways of running multiple sites from a single, common Python web framework (ie: Pylons, TurboGears, etc)? I know you can do redirection based on the domain or path to rewrite the URI to point at a site-specific location and I've also seen some brutish "<code>if site == 'site1' / elseif / elseif / etc</code>" that I would like to avoid.</p>
| 3 | 2008-09-17T16:37:23Z | 85,134 | <p>Django has this built in. See <a href="http://docs.djangoproject.com/en/dev/ref/contrib/sites/#ref-contrib-sites" rel="nofollow">the sites framework</a>.</p>
<p>As a general technique, include a 'host' column in your database schema attached to the data you want to be host-specific, then include the <code>Host</code> HTTP header in the query when you are retrieving data.</p>
| 8 | 2008-09-17T16:39:06Z | [
"python",
"frameworks"
] |
Running multiple sites from a single Python web framework | 85,119 | <p>What are come good (or at least clever) ways of running multiple sites from a single, common Python web framework (ie: Pylons, TurboGears, etc)? I know you can do redirection based on the domain or path to rewrite the URI to point at a site-specific location and I've also seen some brutish "<code>if site == 'site1' / elseif / elseif / etc</code>" that I would like to avoid.</p>
| 3 | 2008-09-17T16:37:23Z | 85,271 | <p>I use CherryPy as my web server (which comes bundled with Turbogears), and I simply run multiple instances of the CherryPy web server on different ports bound to localhost. Then I configure Apache with mod_proxy and mod_rewrite to transparently forward requests to the proper port based on the HTTP request.</p>
| 2 | 2008-09-17T16:52:59Z | [
"python",
"frameworks"
] |
Running multiple sites from a single Python web framework | 85,119 | <p>What are come good (or at least clever) ways of running multiple sites from a single, common Python web framework (ie: Pylons, TurboGears, etc)? I know you can do redirection based on the domain or path to rewrite the URI to point at a site-specific location and I've also seen some brutish "<code>if site == 'site1' / elseif / elseif / etc</code>" that I would like to avoid.</p>
| 3 | 2008-09-17T16:37:23Z | 86,003 | <p>Using multiple server instances on local ports is a good idea, but you don't need a full featured web server to redirect HTTP requests. </p>
<p>I would use <a href="http://www.apsis.ch/pound/" rel="nofollow">pound</a> as a reverse proxy to do the job. It is small, fast, simple and does exactly what we need here.</p>
<blockquote>
<p>WHAT POUND IS:</p>
<ol>
<li><strong>a reverse-proxy: it passes requests from client browsers to one or more back-end servers.</strong></li>
<li>a load balancer: it will distribute the requests from the client browsers among several back-end servers, while keeping session information.</li>
<li>an SSL wrapper: Pound will decrypt HTTPS requests from client browsers and pass them as plain HTTP to the back-end servers.</li>
<li>an HTTP/HTTPS sanitizer: Pound will verify requests for correctness and accept only well-formed ones.</li>
<li>a fail over-server: should a back-end server fail, Pound will take note of the fact and stop passing requests to it until it recovers.</li>
<li><strong>a request redirector: requests may be distributed among servers according to the requested URL.</strong></li>
</ol>
</blockquote>
| 1 | 2008-09-17T18:10:57Z | [
"python",
"frameworks"
] |
Running multiple sites from a single Python web framework | 85,119 | <p>What are come good (or at least clever) ways of running multiple sites from a single, common Python web framework (ie: Pylons, TurboGears, etc)? I know you can do redirection based on the domain or path to rewrite the URI to point at a site-specific location and I've also seen some brutish "<code>if site == 'site1' / elseif / elseif / etc</code>" that I would like to avoid.</p>
| 3 | 2008-09-17T16:37:23Z | 86,705 | <p>Using Django on apache with mod_python, I host multiple (unrelated) django sites simply with the following apache config:</p>
<pre><code><VirtualHost 1.2.3.4>
DocumentRoot /www/site1
ServerName site1.com
<Location />
SetHandler python-program
SetEnv DJANGO_SETTINGS_MODULE site1.settings
PythonPath "['/www'] + sys.path"
PythonDebug On
PythonInterpreter site1
</Location>
</VirtualHost>
<VirtualHost 1.2.3.4>
DocumentRoot /www/site2
ServerName site2.com
<Location />
SetHandler python-program
SetEnv DJANGO_SETTINGS_MODULE site2.settings
PythonPath "['/www'] + sys.path"
PythonDebug On
PythonInterpreter site2
</Location>
</VirtualHost>
</code></pre>
<p>No need for multiple apache instances or proxy servers. Using a different PythonInterpreter directive for each site (the name you enter is arbitrary) keeps the namespaces separate.</p>
| 6 | 2008-09-17T19:29:30Z | [
"python",
"frameworks"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 85,480 | <p>Depends on what you care about. If you mean WALL TIME (as in, the time on the clock on your wall), time.clock() provides NO accuracy because it may manage CPU time. </p>
| 13 | 2008-09-17T17:12:29Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 85,489 | <pre><code>clock() -> floating point number
Return the CPU time or real time since the start of the process or since
the first call to clock(). This has as much precision as the system
records.
time() -> floating point number
Return the current time in seconds since the Epoch.
Fractions of a second may be present if the system clock provides them.
</code></pre>
<p>Usually time() is more precise, because operating systems do not store the process running time with the precision they store the system time (ie, actual time)</p>
| 12 | 2008-09-17T17:14:08Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 85,511 | <p>The short answer is: most of the time time.clock() will be better.
However, if you're timing some hardware (for example some algorithm you put in the GPU), then time.clock() will get rid of this time and time.time() is the only solution left.</p>
<p>Note: whatever the method used, the timing will depend on factors you cannot control (when will the process switch, how often, ...), this is worse with time.time() but exists also with time.clock(), so you should never run one timing test only, but always run a series of test and look at mean/variance of the times.</p>
| 33 | 2008-09-17T17:16:00Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 85,529 | <p>Short answer: use <strong>time.clock()</strong> for timing in Python.</p>
<p>On *nix systems, clock() returns the processor time as a floating point number, expressed in seconds. On Windows, it returns the seconds elapsed since the first call to this function, as a floating point number.</p>
<p>time() returns the the seconds since the epoch, in UTC, as a floating point number. There is no guarantee that you will get a better precision that 1 second (even though time() returns a floating point number). Also note that if the system clock has been set back between two calls to this function, the second function call will return a lower value.</p>
| 2 | 2008-09-17T17:17:57Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 85,533 | <p>As of 3.3, <a href="https://docs.python.org/3/library/time.html#time.clock"><em>time.clock()</em> is deprecated</a>, and it's suggested to use <strong><a href="https://docs.python.org/3/library/time.html#time.process_time">time.process_time()</a></strong> or <strong><a href="https://docs.python.org/3/library/time.html#time.perf_counter">time.perf_counter()</a></strong> instead.</p>
<p>Previously in 2.7, according to the <strong><a href="https://docs.python.org/2.7/library/time.html#time.clock">time module docs</a></strong>:</p>
<blockquote>
<p><strong>time.clock()</strong></p>
<p>On Unix, return the current processor time as a floating point number
expressed in seconds. The precision, and in fact the very definition
of the meaning of âprocessor timeâ, depends on that of the C function
of the same name, but in any case, <strong>this is the function to use for
benchmarking Python or timing algorithms.</strong></p>
<p>On Windows, this function returns wall-clock seconds elapsed since the
first call to this function, as a floating point number, based on the
Win32 function QueryPerformanceCounter(). The resolution is typically
better than one microsecond.</p>
</blockquote>
<p>Additionally, there is the <a href="https://docs.python.org/2/library/timeit.html">timeit</a> module for benchmarking code snippets.</p>
| 91 | 2008-09-17T17:18:27Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 85,536 | <p><a href="http://stackoverflow.com/questions/85451#85511">Others</a> have answered re: time.time() vs. time.clock(). </p>
<p>However, if you're timing the execution of a block of code for benchmarking/profiling purposes, you should take a look at the <a href="https://docs.python.org/library/timeit.html" rel="nofollow"><code>timeit</code> module</a>.</p>
| 20 | 2008-09-17T17:18:56Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 85,586 | <p>On Unix time.clock() measures the amount of CPU time that has been used by the current process, so it's no good for measuring elapsed time from some point in the past. On Windows it will measure wall-clock seconds elapsed since the first call to the function. On either system time.time() will return seconds passed since the epoch. </p>
<p>If you're writing code that's meant only for Windows, either will work (though you'll use the two differently - no subtraction is necessary for time.clock()). If this is going to run on a Unix system or you want code that is guaranteed to be portable, you will want to use time.time().</p>
| 3 | 2008-09-17T17:24:37Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 85,642 | <p>The difference is very platform-specific.</p>
<p>clock() is very different on Windows than on Linux, for example.</p>
<p>For the sort of examples you describe, you probably want the "timeit" module instead.</p>
| 5 | 2008-09-17T17:32:27Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 87,039 | <p>To the best of my understanding, time.clock() has as much precision as your system will allow it.</p>
| 2 | 2008-09-17T20:03:49Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 2,246,226 | <p>One thing to keep in mind:
Changing the system time affects time.time() but not time.clock().</p>
<p>I needed to control some automatic tests executions. If one step of the test case took more than a given amount of time, that TC was aborted to go on with the next one.</p>
<p>But sometimes a step needed to change the system time (to check the scheduler module of the application under test), so after setting the system time a few hours in the future, the TC timeout expired and the test case was aborted. I had to switch from time.time() to time.clock() to handle this properly.</p>
| 16 | 2010-02-11T17:21:26Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 5,087,351 | <p>Use the time.time() is preferred.</p>
| 0 | 2011-02-23T05:30:55Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 21,178,451 | <p>For my own <code>practice. time()</code> has better precision than <code>clock()</code> on Linux. <code>clock()</code> only has precision less than 10 ms. While <code>time()</code> gives prefect precision.
My test is on CentOS 6.4ï¼ python 2.6</p>
<pre><code>using time():
1 requests, response time: 14.1749382019 ms
2 requests, response time: 8.01301002502 ms
3 requests, response time: 8.01491737366 ms
4 requests, response time: 8.41021537781 ms
5 requests, response time: 8.38804244995 ms
</code></pre>
<p><code>using clock():</code></p>
<pre><code>1 requests, response time: 10.0 ms
2 requests, response time: 0.0 ms
3 requests, response time: 0.0 ms
4 requests, response time: 10.0 ms
5 requests, response time: 0.0 ms
6 requests, response time: 0.0 ms
7 requests, response time: 0.0 ms
8 requests, response time: 0.0 ms
</code></pre>
| 9 | 2014-01-17T05:21:01Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 21,374,146 | <p>Comparing test result between Ubuntu Linux and Windows 7.</p>
<p><strong>On Ubuntu</strong></p>
<pre><code>>>> start = time.time(); time.sleep(0.5); (time.time() - start)
0.5005500316619873
</code></pre>
<p><strong>On Windows 7</strong></p>
<pre><code>>>> start = time.time(); time.sleep(0.5); (time.time() - start)
0.5
</code></pre>
| 0 | 2014-01-27T06:13:18Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 35,929,913 | <p>I use this code to compare 2 methods .My OS is windows 8 , processor core i5 , RAM 4GB</p>
<pre><code>import time
def t_time():
start=time.time()
time.sleep(0.1)
return (time.time()-start)
def t_clock():
start=time.clock()
time.sleep(0.1)
return (time.clock()-start)
counter_time=0
counter_clock=0
for i in range(1,100):
counter_time += t_time()
for i in range(1,100):
counter_clock += t_clock()
print "time() =",counter_time/100
print "clock() =",counter_clock/100
</code></pre>
<p>output:</p>
<p>time() = 0.0993799996376</p>
<p>clock() = 0.0993572257367</p>
| 1 | 2016-03-11T00:15:17Z | [
"python"
] |
Python - time.clock() vs. time.time() - accuracy? | 85,451 | <p>Which is better to use for timing in Python? time.clock() or time.time()? Which one provides more accuracy?</p>
<p>for example:</p>
<pre><code>start = time.clock()
... do something
elapsed = (time.clock() - start)
</code></pre>
<p>vs.</p>
<pre><code>start = time.time()
... do something
elapsed = (time.time() - start)
</code></pre>
| 333 | 2008-09-17T17:09:13Z | 38,482,635 | <p>To extend on @Hill's results, here's a test using python 2.7.6 on Xubuntu 14.04 through wine:<br>
(timeit.default_timer will use time.clock() because it sees the OS as 'win32')</p>
<pre><code>>>> from time import sleep, time, clock
>>> start = clock(); sleep(0.5); (clock() - start) # result is never the same:
0.5009140000000087
>>> start = time(); sleep(0.5); (time() - start) # pretty solid result:
0.500999927520752
>>>
</code></pre>
<p>Note, my laptop is slow and I'm currently hosting 3 servers while running 5 resource-hungry tabs in chromium with alot of extensions.<br>
So yes, I have alot of overhead making this look like it's taking more time than it should.</p>
| -1 | 2016-07-20T13:26:53Z | [
"python"
] |
Search for host with MAC-address using Python | 85,577 | <p>I'd like to search for a given MAC address on my network, all from within a Python script. I already have a map of all the active IP addresses in the network but I cannot figure out how to glean the MAC address. Any ideas?</p>
| 8 | 2008-09-17T17:23:23Z | 85,608 | <p>I don't think there is a built in way to get it from Python itself. </p>
<p>My question is, how are you getting the IP information from your network?</p>
<p>To get it from your local machine you could parse ifconfig (unix) or ipconfig (windows) with little difficulty.</p>
| 1 | 2008-09-17T17:27:49Z | [
"python",
"network-programming"
] |
Search for host with MAC-address using Python | 85,577 | <p>I'd like to search for a given MAC address on my network, all from within a Python script. I already have a map of all the active IP addresses in the network but I cannot figure out how to glean the MAC address. Any ideas?</p>
| 8 | 2008-09-17T17:23:23Z | 85,613 | <p>You need <a href="http://en.wikipedia.org/wiki/Address_Resolution_Protocol">ARP</a>. Python's standard library doesn't include any code for that, so you either need to call an external program (your OS may have an 'arp' utility) or you need to build the packets yourself (possibly with a tool like <a href="http://www.secdev.org/projects/scapy/">Scapy</a>.</p>
| 11 | 2008-09-17T17:28:21Z | [
"python",
"network-programming"
] |
Search for host with MAC-address using Python | 85,577 | <p>I'd like to search for a given MAC address on my network, all from within a Python script. I already have a map of all the active IP addresses in the network but I cannot figure out how to glean the MAC address. Any ideas?</p>
| 8 | 2008-09-17T17:23:23Z | 85,620 | <p>Depends on your platform. If you're using *nix, you can use the 'arp' command to look up the mac address for a given IP (assuming IPv4) address. If that doesn't work, you could ping the address and then look, or if you have access to the raw network (using BPF or some other mechanism), you could send your own ARP packets (but that is probably overkill).</p>
| 0 | 2008-09-17T17:29:29Z | [
"python",
"network-programming"
] |
Search for host with MAC-address using Python | 85,577 | <p>I'd like to search for a given MAC address on my network, all from within a Python script. I already have a map of all the active IP addresses in the network but I cannot figure out how to glean the MAC address. Any ideas?</p>
| 8 | 2008-09-17T17:23:23Z | 85,632 | <p>If you want a pure Python solution, you can take a look at <a href="http://www.secdev.org/projects/scapy/" rel="nofollow">Scapy</a> to craft packets (you need to send ARP request, and inspect replies). Or if you don't mind invoking external program, you can use <code>arping</code> (on Un*x systems, I don't know of a Windows equivalent).</p>
| 1 | 2008-09-17T17:30:54Z | [
"python",
"network-programming"
] |
Search for host with MAC-address using Python | 85,577 | <p>I'd like to search for a given MAC address on my network, all from within a Python script. I already have a map of all the active IP addresses in the network but I cannot figure out how to glean the MAC address. Any ideas?</p>
| 8 | 2008-09-17T17:23:23Z | 85,634 | <p>It seems that there is not a native way of doing this with Python. Your best bet would be to parse the output of "ipconfig /all" on Windows, or "ifconfig" on Linux. Consider using os.popen() with some regexps.</p>
| 1 | 2008-09-17T17:31:18Z | [
"python",
"network-programming"
] |
Search for host with MAC-address using Python | 85,577 | <p>I'd like to search for a given MAC address on my network, all from within a Python script. I already have a map of all the active IP addresses in the network but I cannot figure out how to glean the MAC address. Any ideas?</p>
| 8 | 2008-09-17T17:23:23Z | 85,641 | <p>You would want to parse the output of 'arp', but the kernel ARP cache will only contain those IP address(es) if those hosts have communicated with the host where the Python script is running.</p>
<p>ifconfig can be used to display the MAC addresses of local interfaces, but not those on the LAN.</p>
| 0 | 2008-09-17T17:32:21Z | [
"python",
"network-programming"
] |
Search for host with MAC-address using Python | 85,577 | <p>I'd like to search for a given MAC address on my network, all from within a Python script. I already have a map of all the active IP addresses in the network but I cannot figure out how to glean the MAC address. Any ideas?</p>
| 8 | 2008-09-17T17:23:23Z | 85,707 | <p>Mark Pilgrim describes how to do this on Windows for the current machine with the Netbios module <a href="http://groups.google.com/group/comp.lang.python/msg/fd2e7437d72c1c21" rel="nofollow">here</a>. You can get the Netbios module as part of the Win32 package available at python.org. Unfortunately at the moment I cannot find the docs on the module.</p>
| 0 | 2008-09-17T17:38:25Z | [
"python",
"network-programming"
] |
Search for host with MAC-address using Python | 85,577 | <p>I'd like to search for a given MAC address on my network, all from within a Python script. I already have a map of all the active IP addresses in the network but I cannot figure out how to glean the MAC address. Any ideas?</p>
| 8 | 2008-09-17T17:23:23Z | 86,541 | <p>as python was not meant to deal with OS-specific issues (it's supposed to be interpreted and cross platform), I would execute an external command to do so:</p>
<p>in unix the command is <code>ifconfig</code></p>
<p>if you execute it as a pipe you get the desired result:</p>
<pre><code>import os;
myPipe=os.popen2("/sbin/ifconfig","a");
print(myPipe[1].read());
</code></pre>
| -1 | 2008-09-17T19:13:45Z | [
"python",
"network-programming"
] |
Search for host with MAC-address using Python | 85,577 | <p>I'd like to search for a given MAC address on my network, all from within a Python script. I already have a map of all the active IP addresses in the network but I cannot figure out how to glean the MAC address. Any ideas?</p>
| 8 | 2008-09-17T17:23:23Z | 89,809 | <p><a href="http://www.larsen-b.com/Article/206.html" rel="nofollow">This article</a>, "Send hand-crafted Ethernet Frames in Python (ARP for example)", seems to be exactly what you are looking for.</p>
| 3 | 2008-09-18T03:43:03Z | [
"python",
"network-programming"
] |
How to best implement simple crash / error reporting? | 85,985 | <p>What would be the best way to implement a simple crash / error reporting mechanism? </p>
<p>Details: my app is <strong>cross-platform (mac/windows/linux) and written in Python</strong>, so I just need something that will send me a small amount of text, e.g. just a timestamp and a traceback (which I already generate and show in my error dialog). </p>
<p>It would be fine if it could simply email it, but I can't think of a way to do this without including a username and password for the smtp server in the application...
Should I implement a simple web service on the server side and have my app send it an HTTP request with the info? Any better ideas?</p>
<p>Thanks!</p>
| 8 | 2008-09-17T18:09:32Z | 86,007 | <p>The web hit is the way to go, but make sure you pick a good URL - your app will be hitting it for years to come. </p>
| 1 | 2008-09-17T18:11:53Z | [
"python",
"cross-platform",
"qa",
"error-reporting"
] |
How to best implement simple crash / error reporting? | 85,985 | <p>What would be the best way to implement a simple crash / error reporting mechanism? </p>
<p>Details: my app is <strong>cross-platform (mac/windows/linux) and written in Python</strong>, so I just need something that will send me a small amount of text, e.g. just a timestamp and a traceback (which I already generate and show in my error dialog). </p>
<p>It would be fine if it could simply email it, but I can't think of a way to do this without including a username and password for the smtp server in the application...
Should I implement a simple web service on the server side and have my app send it an HTTP request with the info? Any better ideas?</p>
<p>Thanks!</p>
| 8 | 2008-09-17T18:09:32Z | 86,010 | <p><a href="http://pycrash.sourceforge.net/" rel="nofollow">PyCrash</a>?</p>
| 1 | 2008-09-17T18:12:08Z | [
"python",
"cross-platform",
"qa",
"error-reporting"
] |
How to best implement simple crash / error reporting? | 85,985 | <p>What would be the best way to implement a simple crash / error reporting mechanism? </p>
<p>Details: my app is <strong>cross-platform (mac/windows/linux) and written in Python</strong>, so I just need something that will send me a small amount of text, e.g. just a timestamp and a traceback (which I already generate and show in my error dialog). </p>
<p>It would be fine if it could simply email it, but I can't think of a way to do this without including a username and password for the smtp server in the application...
Should I implement a simple web service on the server side and have my app send it an HTTP request with the info? Any better ideas?</p>
<p>Thanks!</p>
| 8 | 2008-09-17T18:09:32Z | 86,022 | <p>Whether you use SMTP or HTTP to send the data, you need to have a username/password in the application to prevent just anyone from sending random data to you.</p>
<p>With that in mind, I suspect it would be easier to use SMTP rather than HTTP to send the data.</p>
| 0 | 2008-09-17T18:13:09Z | [
"python",
"cross-platform",
"qa",
"error-reporting"
] |
How to best implement simple crash / error reporting? | 85,985 | <p>What would be the best way to implement a simple crash / error reporting mechanism? </p>
<p>Details: my app is <strong>cross-platform (mac/windows/linux) and written in Python</strong>, so I just need something that will send me a small amount of text, e.g. just a timestamp and a traceback (which I already generate and show in my error dialog). </p>
<p>It would be fine if it could simply email it, but I can't think of a way to do this without including a username and password for the smtp server in the application...
Should I implement a simple web service on the server side and have my app send it an HTTP request with the info? Any better ideas?</p>
<p>Thanks!</p>
| 8 | 2008-09-17T18:09:32Z | 86,050 | <p>The web service is the best way, but there are some caveats:</p>
<ol>
<li>You should always ask the user if it is ok to send error feedback information.</li>
<li>You should be prepared to fail gracefully if there are network errors. Don't let a failure to report a crash impede recovery!</li>
<li>You should avoid including user identifying or sensitive information unless the user knows (see #1) and you should either use SSL or otherwise protect it. Some jurisdictions impose burdens on you that you might not want to deal with, so it's best to simply not save such information.</li>
<li>Like any web service, make sure your service is not exploitable by miscreants.</li>
</ol>
| 4 | 2008-09-17T18:16:02Z | [
"python",
"cross-platform",
"qa",
"error-reporting"
] |
How to best implement simple crash / error reporting? | 85,985 | <p>What would be the best way to implement a simple crash / error reporting mechanism? </p>
<p>Details: my app is <strong>cross-platform (mac/windows/linux) and written in Python</strong>, so I just need something that will send me a small amount of text, e.g. just a timestamp and a traceback (which I already generate and show in my error dialog). </p>
<p>It would be fine if it could simply email it, but I can't think of a way to do this without including a username and password for the smtp server in the application...
Should I implement a simple web service on the server side and have my app send it an HTTP request with the info? Any better ideas?</p>
<p>Thanks!</p>
| 8 | 2008-09-17T18:09:32Z | 86,069 | <p>Some kind of simple web service would suffice. You would have to consider security so not just anyone could make requests to your service..</p>
<p>On a larger scale we considered a JMS messaging system. Put a serialized object of data containing the traceback/error message into a queue and consume it every x minutes generating reports/alerts from that data.</p>
| 0 | 2008-09-17T18:17:52Z | [
"python",
"cross-platform",
"qa",
"error-reporting"
] |
How to best implement simple crash / error reporting? | 85,985 | <p>What would be the best way to implement a simple crash / error reporting mechanism? </p>
<p>Details: my app is <strong>cross-platform (mac/windows/linux) and written in Python</strong>, so I just need something that will send me a small amount of text, e.g. just a timestamp and a traceback (which I already generate and show in my error dialog). </p>
<p>It would be fine if it could simply email it, but I can't think of a way to do this without including a username and password for the smtp server in the application...
Should I implement a simple web service on the server side and have my app send it an HTTP request with the info? Any better ideas?</p>
<p>Thanks!</p>
| 8 | 2008-09-17T18:09:32Z | 86,167 | <blockquote>
<p>I can't think of a way to do this without including a username and password for the smtp server in the application...</p>
</blockquote>
<p>You only need a username and password for authenticating yourself to a smarthost. You don't need it to send mail directly, you need it to send mail through a relay, e.g. your ISP's mail server. It's perfectly possible to send email without authentication - that's why spam is so hard to stop.</p>
<p>Having said that, some ISPs block outbound traffic on port 25, so the most robust alternative is an HTTP POST, which is unlikely to be blocked by anything. Be sure to pick a URL that you won't feel restricted by later on, or better yet, have the application periodically check for updates, so if you decide to change domains or something, you can push an update in advance.</p>
<p>Security isn't really an issue. You can fairly easily discard junk data, so all that really concerns you is whether or not somebody would go to the trouble of constructing fake tracebacks to mess with you, and that's a very unlikely situation.</p>
<p>As for the payload, <a href="http://pycrash.sourceforge.net/" rel="nofollow">PyCrash</a> can help you with that.</p>
| 3 | 2008-09-17T18:30:25Z | [
"python",
"cross-platform",
"qa",
"error-reporting"
] |
What are the pros and cons of the various Python implementations? | 86,134 | <p>I am relatively new to Python, and I have always used the standard cpython (v2.5) implementation. </p>
<p>I've been wondering about the other implementations though, particularly Jython and IronPython. What makes them better? What makes them worse? What other implementations are there?</p>
<p>I guess what I'm looking for is a summary and list of pros and cons for each implementation.</p>
| 9 | 2008-09-17T18:25:28Z | 86,172 | <p>Pros: Access to the libraries available for JVM or CLR.</p>
<p>Cons: Both naturally lag behind CPython in terms of features.</p>
| 1 | 2008-09-17T18:30:41Z | [
"python"
] |
What are the pros and cons of the various Python implementations? | 86,134 | <p>I am relatively new to Python, and I have always used the standard cpython (v2.5) implementation. </p>
<p>I've been wondering about the other implementations though, particularly Jython and IronPython. What makes them better? What makes them worse? What other implementations are there?</p>
<p>I guess what I'm looking for is a summary and list of pros and cons for each implementation.</p>
| 9 | 2008-09-17T18:25:28Z | 86,173 | <p><strong>Jython</strong> and <strong>IronPython</strong> are useful if you have an overriding need to interface with existing libraries written in a different platform, like if you have 100,000 lines of Java and you just want to write a 20-line Python script. Not particularly useful for anything else, in my opinion, because they are perpetually a few versions behind CPython due to community inertia.</p>
<p><strong>Stackless</strong> is interesting because it has support for green threads, continuations, etc. Sort of an Erlang-lite.</p>
<p><strong>PyPy</strong> is an experimental interpreter/compiler that may one day supplant CPython, but for now is more of a testbed for new ideas.</p>
| 15 | 2008-09-17T18:31:21Z | [
"python"
] |
What are the pros and cons of the various Python implementations? | 86,134 | <p>I am relatively new to Python, and I have always used the standard cpython (v2.5) implementation. </p>
<p>I've been wondering about the other implementations though, particularly Jython and IronPython. What makes them better? What makes them worse? What other implementations are there?</p>
<p>I guess what I'm looking for is a summary and list of pros and cons for each implementation.</p>
| 9 | 2008-09-17T18:25:28Z | 86,186 | <p>All of the implementations are listed here:</p>
<p><a href="https://wiki.python.org/moin/PythonImplementations" rel="nofollow">https://wiki.python.org/moin/PythonImplementations</a></p>
<p>CPython is the "reference implementation" and developed by Guido and the core developers.</p>
| 3 | 2008-09-17T18:33:09Z | [
"python"
] |
What are the pros and cons of the various Python implementations? | 86,134 | <p>I am relatively new to Python, and I have always used the standard cpython (v2.5) implementation. </p>
<p>I've been wondering about the other implementations though, particularly Jython and IronPython. What makes them better? What makes them worse? What other implementations are there?</p>
<p>I guess what I'm looking for is a summary and list of pros and cons for each implementation.</p>
| 9 | 2008-09-17T18:25:28Z | 86,427 | <p>IronPython and Jython use the runtime environment for .NET or Java and with that comes Just In Time compilation and a garbage collector different from the original CPython. They might be also faster than CPython thanks to the JIT, but I don't know that for sure.</p>
<p>A downside in using Jython or IronPython is that you cannot use native C modules, they can be only used in CPython.</p>
| 1 | 2008-09-17T19:00:15Z | [
"python"
] |
What are the pros and cons of the various Python implementations? | 86,134 | <p>I am relatively new to Python, and I have always used the standard cpython (v2.5) implementation. </p>
<p>I've been wondering about the other implementations though, particularly Jython and IronPython. What makes them better? What makes them worse? What other implementations are there?</p>
<p>I guess what I'm looking for is a summary and list of pros and cons for each implementation.</p>
| 9 | 2008-09-17T18:25:28Z | 86,665 | <p><a href="http://codespeak.net/pypy/dist/pypy/doc/home.html" rel="nofollow">PyPy</a> is a Python implementation written in RPython wich is a Python subset. </p>
<p>RPython can be translated to run on a VM or, unlike standard Python, RPython can be statically compiled.</p>
| 1 | 2008-09-17T19:26:12Z | [
"python"
] |
What are the pros and cons of the various Python implementations? | 86,134 | <p>I am relatively new to Python, and I have always used the standard cpython (v2.5) implementation. </p>
<p>I've been wondering about the other implementations though, particularly Jython and IronPython. What makes them better? What makes them worse? What other implementations are there?</p>
<p>I guess what I'm looking for is a summary and list of pros and cons for each implementation.</p>
| 9 | 2008-09-17T18:25:28Z | 90,103 | <p>An additional benefit for Jython, at least for some, is <a href="http://zyasoft.com/pythoneering/2008/06/realizing-jython-25.html">it lacks the GIL</a> (the Global Interpreter Lock) and uses Java's native threads. This means that you can run pure Python code in parallel, something not possible with the GIL.</p>
| 6 | 2008-09-18T04:44:08Z | [
"python"
] |
Get list of XML attribute values in Python | 87,317 | <p>I need to get a list of attribute values from child elements in Python.</p>
<p>It's easiest to explain with an example.</p>
<p>Given some XML like this:</p>
<pre><code><elements>
<parent name="CategoryA">
<child value="a1"/>
<child value="a2"/>
<child value="a3"/>
</parent>
<parent name="CategoryB">
<child value="b1"/>
<child value="b2"/>
<child value="b3"/>
</parent>
</elements>
</code></pre>
<p>I want to be able to do something like:</p>
<pre class="lang-python prettyprint-override"><code>>>> getValues("CategoryA")
['a1', 'a2', 'a3']
>>> getValues("CategoryB")
['b1', 'b2', 'b3']
</code></pre>
<p>It looks like a job for XPath but I'm open to all recommendations. I'd also like to hear about your favourite Python XML libraries.</p>
| 10 | 2008-09-17T20:32:04Z | 87,503 | <p>I must admit I'm a fan of <a href="http://www.aaronsw.com/2002/xmltramp/" rel="nofollow">xmltramp</a> due to its ease of use.</p>
<p>Accessing the above becomes:</p>
<pre><code> import xmltramp
values = xmltramp.parse('''...''')
def getValues( values, category ):
cat = [ parent for parent in values['parent':] if parent(name) == category ]
cat_values = [ child(value) for child in parent['child':] for parent in cat ]
return cat_values
getValues( values, "CategoryA" )
getValues( values, "CategoryB" )
</code></pre>
| 2 | 2008-09-17T20:47:15Z | [
"python",
"xml",
"xpath",
"parent-child",
"xml-attribute"
] |
Get list of XML attribute values in Python | 87,317 | <p>I need to get a list of attribute values from child elements in Python.</p>
<p>It's easiest to explain with an example.</p>
<p>Given some XML like this:</p>
<pre><code><elements>
<parent name="CategoryA">
<child value="a1"/>
<child value="a2"/>
<child value="a3"/>
</parent>
<parent name="CategoryB">
<child value="b1"/>
<child value="b2"/>
<child value="b3"/>
</parent>
</elements>
</code></pre>
<p>I want to be able to do something like:</p>
<pre class="lang-python prettyprint-override"><code>>>> getValues("CategoryA")
['a1', 'a2', 'a3']
>>> getValues("CategoryB")
['b1', 'b2', 'b3']
</code></pre>
<p>It looks like a job for XPath but I'm open to all recommendations. I'd also like to hear about your favourite Python XML libraries.</p>
| 10 | 2008-09-17T20:32:04Z | 87,543 | <p>You can do this with <a href="http://www.crummy.com/software/BeautifulSoup/" rel="nofollow">BeautifulSoup</a></p>
<pre><code>>>> from BeautifulSoup import BeautifulStoneSoup
>>> soup = BeautifulStoneSoup(xml)
>>> def getValues(name):
. . . return [child['value'] for child in soup.find('parent', attrs={'name': name}).findAll('child')]
</code></pre>
<p>If you're doing work with HTML/XML I would recommend you take a look at BeautifulSoup. It's similar to the DOM tree but contains more functionality.</p>
| 2 | 2008-09-17T20:50:51Z | [
"python",
"xml",
"xpath",
"parent-child",
"xml-attribute"
] |
Get list of XML attribute values in Python | 87,317 | <p>I need to get a list of attribute values from child elements in Python.</p>
<p>It's easiest to explain with an example.</p>
<p>Given some XML like this:</p>
<pre><code><elements>
<parent name="CategoryA">
<child value="a1"/>
<child value="a2"/>
<child value="a3"/>
</parent>
<parent name="CategoryB">
<child value="b1"/>
<child value="b2"/>
<child value="b3"/>
</parent>
</elements>
</code></pre>
<p>I want to be able to do something like:</p>
<pre class="lang-python prettyprint-override"><code>>>> getValues("CategoryA")
['a1', 'a2', 'a3']
>>> getValues("CategoryB")
['b1', 'b2', 'b3']
</code></pre>
<p>It looks like a job for XPath but I'm open to all recommendations. I'd also like to hear about your favourite Python XML libraries.</p>
| 10 | 2008-09-17T20:32:04Z | 87,622 | <p>I'm not really an old hand at Python, but here's an XPath solution using libxml2.</p>
<pre><code>import libxml2
DOC = """<elements>
<parent name="CategoryA">
<child value="a1"/>
<child value="a2"/>
<child value="a3"/>
</parent>
<parent name="CategoryB">
<child value="b1"/>
<child value="b2"/>
<child value="b3"/>
</parent>
</elements>"""
doc = libxml2.parseDoc(DOC)
def getValues(cat):
return [attr.content for attr in doc.xpathEval("/elements/parent[@name='%s']/child/@value" % (cat))]
print getValues("CategoryA")
</code></pre>
<p>With result...</p>
<pre><code>['a1', 'a2', 'a3']
</code></pre>
| 7 | 2008-09-17T21:00:32Z | [
"python",
"xml",
"xpath",
"parent-child",
"xml-attribute"
] |
Get list of XML attribute values in Python | 87,317 | <p>I need to get a list of attribute values from child elements in Python.</p>
<p>It's easiest to explain with an example.</p>
<p>Given some XML like this:</p>
<pre><code><elements>
<parent name="CategoryA">
<child value="a1"/>
<child value="a2"/>
<child value="a3"/>
</parent>
<parent name="CategoryB">
<child value="b1"/>
<child value="b2"/>
<child value="b3"/>
</parent>
</elements>
</code></pre>
<p>I want to be able to do something like:</p>
<pre class="lang-python prettyprint-override"><code>>>> getValues("CategoryA")
['a1', 'a2', 'a3']
>>> getValues("CategoryB")
['b1', 'b2', 'b3']
</code></pre>
<p>It looks like a job for XPath but I'm open to all recommendations. I'd also like to hear about your favourite Python XML libraries.</p>
| 10 | 2008-09-17T20:32:04Z | 87,651 | <p>Using a standard W3 DOM such as the stdlib's minidom, or pxdom:</p>
<pre><code>def getValues(category):
for parent in document.getElementsByTagName('parent'):
if parent.getAttribute('name')==category:
return [
el.getAttribute('value')
for el in parent.getElementsByTagName('child')
]
raise ValueError('parent not found')
</code></pre>
| 3 | 2008-09-17T21:04:42Z | [
"python",
"xml",
"xpath",
"parent-child",
"xml-attribute"
] |
Get list of XML attribute values in Python | 87,317 | <p>I need to get a list of attribute values from child elements in Python.</p>
<p>It's easiest to explain with an example.</p>
<p>Given some XML like this:</p>
<pre><code><elements>
<parent name="CategoryA">
<child value="a1"/>
<child value="a2"/>
<child value="a3"/>
</parent>
<parent name="CategoryB">
<child value="b1"/>
<child value="b2"/>
<child value="b3"/>
</parent>
</elements>
</code></pre>
<p>I want to be able to do something like:</p>
<pre class="lang-python prettyprint-override"><code>>>> getValues("CategoryA")
['a1', 'a2', 'a3']
>>> getValues("CategoryB")
['b1', 'b2', 'b3']
</code></pre>
<p>It looks like a job for XPath but I'm open to all recommendations. I'd also like to hear about your favourite Python XML libraries.</p>
| 10 | 2008-09-17T20:32:04Z | 87,658 | <p><a href="http://effbot.org/zone/elementtree-13-intro.htm">ElementTree 1.3</a> (unfortunately not 1.2 which is the one included with Python) <a href="http://effbot.org/zone/element-xpath.htm">supports XPath</a> like this:</p>
<pre><code>import elementtree.ElementTree as xml
def getValues(tree, category):
parent = tree.find(".//parent[@name='%s']" % category)
return [child.get('value') for child in parent]
</code></pre>
<p>Then you can do </p>
<pre><code>>>> tree = xml.parse('data.xml')
>>> getValues(tree, 'CategoryA')
['a1', 'a2', 'a3']
>>> getValues(tree, 'CategoryB')
['b1', 'b2', 'b3']
</code></pre>
<p><code>lxml.etree</code> (which also provides the ElementTree interface) will also work in the same way.</p>
| 5 | 2008-09-17T21:05:38Z | [
"python",
"xml",
"xpath",
"parent-child",
"xml-attribute"
] |
Get list of XML attribute values in Python | 87,317 | <p>I need to get a list of attribute values from child elements in Python.</p>
<p>It's easiest to explain with an example.</p>
<p>Given some XML like this:</p>
<pre><code><elements>
<parent name="CategoryA">
<child value="a1"/>
<child value="a2"/>
<child value="a3"/>
</parent>
<parent name="CategoryB">
<child value="b1"/>
<child value="b2"/>
<child value="b3"/>
</parent>
</elements>
</code></pre>
<p>I want to be able to do something like:</p>
<pre class="lang-python prettyprint-override"><code>>>> getValues("CategoryA")
['a1', 'a2', 'a3']
>>> getValues("CategoryB")
['b1', 'b2', 'b3']
</code></pre>
<p>It looks like a job for XPath but I'm open to all recommendations. I'd also like to hear about your favourite Python XML libraries.</p>
| 10 | 2008-09-17T20:32:04Z | 87,726 | <p>My preferred python xml library is <a href="http://codespeak.net/lxml" rel="nofollow">lxml</a> , which wraps libxml2.<br />
Xpath does seem the way to go here, so I'd write this as something like:</p>
<pre><code>from lxml import etree
def getValues(xml, category):
return [x.attrib['value'] for x in
xml.findall('/parent[@name="%s"]/*' % category)]
xml = etree.parse(open('filename.xml'))
>>> print getValues(xml, 'CategoryA')
['a1', 'a2', 'a3']
>>> print getValues(xml, 'CategoryB')
['b1', 'b2', 'b3]
</code></pre>
| 2 | 2008-09-17T21:12:16Z | [
"python",
"xml",
"xpath",
"parent-child",
"xml-attribute"
] |
If it is decided that our system needs an overhaul, what is the best way to go about it? | 87,522 | <p>We are mainting a web application that is built on Classic ASP using VBScript as the primary language. We are in agreement that our backend (framework if you will) is out dated and doesn't provide us with the proper tools to move forward in a quick manner. We have pretty much embraced the current webMVC pattern that is all over the place, and cannot do it, in a reasonable manner, with the current technology. The big missing features are proper dispatching and templating with inheritance, amongst others.</p>
<p>Currently there are two paths being discussed:</p>
<ol>
<li>Port the existing application to Classic ASP using JScript, which will allow us to hopefully go from there to .NET MSJscript without too much trouble, and eventually end up on the .NET platform (preferably the MVC stuff will be done by then, ASP.NET isn't much better than were we are on now, in our opinions). This has been argued as the safer path with less risk than the next option, albeit it might take slightly longer.</li>
<li>Completely rewrite the application using some other technology, right now the leader of the pack is Python WSGI with a custom framework, ORM, and a good templating solution. There is wiggle room here for even django and other pre-built solutions. This method would hopefully be the quickest solution, as we would probably run a beta beside the actual product, but it does have the potential for a big waste of time if we can't/don't get it right.</li>
</ol>
<p>This does not mean that our logic is gone, as what we have built over the years is fairly stable, as noted just difficult to deal with. It is built on SQL Server 2005 with heavy use of stored procedures and published on IIS 6, just for a little more background.</p>
<p>Now, the question. Has anyone taken either of the two paths above? If so, was it successful, how could it have been better, etc. We aren't looking to deviate much from doing one of those two things, but some suggestions or other solutions would potentially be helpful.</p>
| 3 | 2008-09-17T20:48:45Z | 87,562 | <p>Use this as an opportunity to remove unused features! Definitely go with the new language. Call it 2.0. It will be a lot less work to rebuild the 80% of it that you really need.</p>
<p>Start by wiping your brain clean of the whole application. Sit down with a list of its overall goals, then decide which features are needed based on which ones are used. Then redesign it with those features in mind, and build.</p>
<p>(I love to delete code.)</p>
| 3 | 2008-09-17T20:53:43Z | [
"python",
"asp-classic",
"vbscript"
] |
If it is decided that our system needs an overhaul, what is the best way to go about it? | 87,522 | <p>We are mainting a web application that is built on Classic ASP using VBScript as the primary language. We are in agreement that our backend (framework if you will) is out dated and doesn't provide us with the proper tools to move forward in a quick manner. We have pretty much embraced the current webMVC pattern that is all over the place, and cannot do it, in a reasonable manner, with the current technology. The big missing features are proper dispatching and templating with inheritance, amongst others.</p>
<p>Currently there are two paths being discussed:</p>
<ol>
<li>Port the existing application to Classic ASP using JScript, which will allow us to hopefully go from there to .NET MSJscript without too much trouble, and eventually end up on the .NET platform (preferably the MVC stuff will be done by then, ASP.NET isn't much better than were we are on now, in our opinions). This has been argued as the safer path with less risk than the next option, albeit it might take slightly longer.</li>
<li>Completely rewrite the application using some other technology, right now the leader of the pack is Python WSGI with a custom framework, ORM, and a good templating solution. There is wiggle room here for even django and other pre-built solutions. This method would hopefully be the quickest solution, as we would probably run a beta beside the actual product, but it does have the potential for a big waste of time if we can't/don't get it right.</li>
</ol>
<p>This does not mean that our logic is gone, as what we have built over the years is fairly stable, as noted just difficult to deal with. It is built on SQL Server 2005 with heavy use of stored procedures and published on IIS 6, just for a little more background.</p>
<p>Now, the question. Has anyone taken either of the two paths above? If so, was it successful, how could it have been better, etc. We aren't looking to deviate much from doing one of those two things, but some suggestions or other solutions would potentially be helpful.</p>
| 3 | 2008-09-17T20:48:45Z | 87,573 | <p>I would not recommend JScript as that is definitely the road less traveled.
ASP.NET MVC is rapidly maturing, and I think that you could begin a migration to it, simultaneously ramping up on the ASP.NET MVC framework as its finalization comes through.
Another option would be to use something like ASP.NET w/Subsonic or NHibernate.</p>
| 0 | 2008-09-17T20:55:23Z | [
"python",
"asp-classic",
"vbscript"
] |
If it is decided that our system needs an overhaul, what is the best way to go about it? | 87,522 | <p>We are mainting a web application that is built on Classic ASP using VBScript as the primary language. We are in agreement that our backend (framework if you will) is out dated and doesn't provide us with the proper tools to move forward in a quick manner. We have pretty much embraced the current webMVC pattern that is all over the place, and cannot do it, in a reasonable manner, with the current technology. The big missing features are proper dispatching and templating with inheritance, amongst others.</p>
<p>Currently there are two paths being discussed:</p>
<ol>
<li>Port the existing application to Classic ASP using JScript, which will allow us to hopefully go from there to .NET MSJscript without too much trouble, and eventually end up on the .NET platform (preferably the MVC stuff will be done by then, ASP.NET isn't much better than were we are on now, in our opinions). This has been argued as the safer path with less risk than the next option, albeit it might take slightly longer.</li>
<li>Completely rewrite the application using some other technology, right now the leader of the pack is Python WSGI with a custom framework, ORM, and a good templating solution. There is wiggle room here for even django and other pre-built solutions. This method would hopefully be the quickest solution, as we would probably run a beta beside the actual product, but it does have the potential for a big waste of time if we can't/don't get it right.</li>
</ol>
<p>This does not mean that our logic is gone, as what we have built over the years is fairly stable, as noted just difficult to deal with. It is built on SQL Server 2005 with heavy use of stored procedures and published on IIS 6, just for a little more background.</p>
<p>Now, the question. Has anyone taken either of the two paths above? If so, was it successful, how could it have been better, etc. We aren't looking to deviate much from doing one of those two things, but some suggestions or other solutions would potentially be helpful.</p>
| 3 | 2008-09-17T20:48:45Z | 87,684 | <p>Whatever you do, see if you can manage to follow a plan where you do not have to port the application all in one big bang. It is tempting to throw it all away and start from scratch, but if you can manage to do it gradually the mistakes you do will not cost so much and cause so much panic.</p>
| 2 | 2008-09-17T21:08:42Z | [
"python",
"asp-classic",
"vbscript"
] |
If it is decided that our system needs an overhaul, what is the best way to go about it? | 87,522 | <p>We are mainting a web application that is built on Classic ASP using VBScript as the primary language. We are in agreement that our backend (framework if you will) is out dated and doesn't provide us with the proper tools to move forward in a quick manner. We have pretty much embraced the current webMVC pattern that is all over the place, and cannot do it, in a reasonable manner, with the current technology. The big missing features are proper dispatching and templating with inheritance, amongst others.</p>
<p>Currently there are two paths being discussed:</p>
<ol>
<li>Port the existing application to Classic ASP using JScript, which will allow us to hopefully go from there to .NET MSJscript without too much trouble, and eventually end up on the .NET platform (preferably the MVC stuff will be done by then, ASP.NET isn't much better than were we are on now, in our opinions). This has been argued as the safer path with less risk than the next option, albeit it might take slightly longer.</li>
<li>Completely rewrite the application using some other technology, right now the leader of the pack is Python WSGI with a custom framework, ORM, and a good templating solution. There is wiggle room here for even django and other pre-built solutions. This method would hopefully be the quickest solution, as we would probably run a beta beside the actual product, but it does have the potential for a big waste of time if we can't/don't get it right.</li>
</ol>
<p>This does not mean that our logic is gone, as what we have built over the years is fairly stable, as noted just difficult to deal with. It is built on SQL Server 2005 with heavy use of stored procedures and published on IIS 6, just for a little more background.</p>
<p>Now, the question. Has anyone taken either of the two paths above? If so, was it successful, how could it have been better, etc. We aren't looking to deviate much from doing one of those two things, but some suggestions or other solutions would potentially be helpful.</p>
| 3 | 2008-09-17T20:48:45Z | 87,998 | <p>It works out better than you'd believe. </p>
<p>Recently I did a large reverse-engineering job on a hideous old collection of C code. Function by function I reallocated the features that were still relevant into classes, wrote unit tests for the classes, and built up what looked like a replacement application. It had some of the original "logic flow" through the classes, and some classes were poorly designed [Mostly this was because of a subset of the global variables that was too hard to tease apart.]</p>
<p>It passed unit tests at the class level and at the overall application level. The legacy source was mostly used as a kind of "specification in C" to ferret out the really obscure business rules.</p>
<p>Last year, I wrote a project plan for replacing 30-year old COBOL. The customer was leaning toward Java. I prototyped the revised data model in Python using Django as part of the planning effort. I could demo the core transactions before I was done planning.</p>
<p><strong>Note</strong>: It was quicker to build a the model and admin interface in Django than to plan the project as a whole.</p>
<p>Because of the "we need to use Java" mentality, the resulting project will be larger and more expensive than finishing the Django demo. With no real value to balance that cost.</p>
<p>Also, I did the same basic "prototype in Django" for a VB desktop application that needed to become a web application. I built the model in Django, loaded legacy data, and was up and running in a few weeks. I used that working prototype to specify the rest of the conversion effort.</p>
<p><strong>Note</strong>: I had a working Django implementation (model and admin pages only) that I used to plan the rest of the effort.</p>
<p>The best part about doing this kind of prototyping in Django is that you can mess around with the model, unit tests and admin pages until you get it <strong>right</strong>. Once the model's right, you can spend the rest of your time fiddling around with the user interface until everyone's happy.</p>
| 3 | 2008-09-17T21:44:51Z | [
"python",
"asp-classic",
"vbscript"
] |
Subsets and Splits