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Will everything in the standard library treat strings as unicode in Python 3.0? | 91,205 | <p>I'm a little confused about how the standard library will behave now that Python (from 3.0) is unicode-based. Will modules such as CGI and urllib use unicode strings or will they use the new 'bytes' type and just provide encoded data?</p>
| 10 | 2008-09-18T09:29:23Z | 91,301 | <p>Logically a lot of things like MIME-encoded mail messages, URLs, XML documents, and so on should be returned as <code>bytes</code> not strings. This could cause some consternation as the libraries start to be nailed down for Python 3 and people discover that they have to be more aware of the <code>bytes</code>/<code>string</code> conversions than they were for <code>str</code>/<code>unicode</code> ...</p>
| 10 | 2008-09-18T09:52:48Z | [
"python",
"unicode",
"string",
"cgi",
"python-3.x"
] |
Will everything in the standard library treat strings as unicode in Python 3.0? | 91,205 | <p>I'm a little confused about how the standard library will behave now that Python (from 3.0) is unicode-based. Will modules such as CGI and urllib use unicode strings or will they use the new 'bytes' type and just provide encoded data?</p>
| 10 | 2008-09-18T09:29:23Z | 91,325 | <p>One of the great things about this question (and Python in general) is that you can just mess around in the interpreter! <a href="http://www.python.org/download/releases/3.0/">Python 3.0 rc1 is currently available for download</a>.</p>
<pre><code>>>> import urllib.request
>>> fh = urllib.request.urlopen('http://www.python.org/')
>>> print(type(fh.read(100)))
<class 'bytes'>
</code></pre>
| 6 | 2008-09-18T09:58:19Z | [
"python",
"unicode",
"string",
"cgi",
"python-3.x"
] |
Will everything in the standard library treat strings as unicode in Python 3.0? | 91,205 | <p>I'm a little confused about how the standard library will behave now that Python (from 3.0) is unicode-based. Will modules such as CGI and urllib use unicode strings or will they use the new 'bytes' type and just provide encoded data?</p>
| 10 | 2008-09-18T09:29:23Z | 91,508 | <p>There will be a two-step dance here. See <a href="http://www.artima.com/weblogs/viewpost.jsp?thread=227041" rel="nofollow">Python 3000 and You</a>.</p>
<p>Step 1 is to get running under 3.0.</p>
<p>Step 2 is to rethink your API's to, perhaps, do something more sensible.</p>
<p>The most likely course is that the libraries will switch to unicode strings to remain as compatible as possible with how they used to work.</p>
<p>Then, perhaps, some will switch to bytes to more properly implement the RFC standards for the various protocols.</p>
| 1 | 2008-09-18T10:35:07Z | [
"python",
"unicode",
"string",
"cgi",
"python-3.x"
] |
NI CVI with Python | 91,666 | <p>I'd like to integrate a Python IDLE-esque command prompt interface into an existing NI-CVI (LabWindows) application. I've tried to follow the Python.org discussions but seem to get lost in the details. Is there a resource out there for dummies like me?</p>
| 2 | 2008-09-18T11:09:50Z | 91,735 | <p>Here is a <a href="http://decibel.ni.com/content/docs/DOC-1494" rel="nofollow">python sample code calling a CVI</a>.</p>
<p>There are <a href="http://www.scipy.org/Cookbook/Data_Acquisition_with_PyUL" rel="nofollow">DaqMx python bindings</a> too.</p>
| 1 | 2008-09-18T11:22:06Z | [
"python",
"labview",
"labwindows",
"cvi"
] |
Is there a pretty printer for python data? | 91,810 | <p>Working with python interactively, it's sometimes necessary to display a result which is some arbitrarily complex data structure (like lists with embedded lists, etc.)
The default way to display them is just one massive linear dump which just wraps over and over and you have to parse carefully to read it.</p>
<p>Is there something that will take any python object and display it in a more rational manner. e.g.</p>
<pre><code>[0, 1,
[a, b, c],
2, 3, 4]
</code></pre>
<p>instead of:</p>
<pre><code>[0, 1, [a, b, c], 2, 3, 4]
</code></pre>
<p>I know that's not a very good example, but I think you get the idea.</p>
| 16 | 2008-09-18T11:43:45Z | 91,818 | <pre><code>from pprint import pprint
a = [0, 1, ['a', 'b', 'c'], 2, 3, 4]
pprint(a)
</code></pre>
<p>Note that for a short list like my example, pprint will in fact print it all on one line. However, for more complex structures it does a pretty good job of pretty printing data.</p>
| 24 | 2008-09-18T11:44:54Z | [
"python",
"prettify"
] |
Is there a pretty printer for python data? | 91,810 | <p>Working with python interactively, it's sometimes necessary to display a result which is some arbitrarily complex data structure (like lists with embedded lists, etc.)
The default way to display them is just one massive linear dump which just wraps over and over and you have to parse carefully to read it.</p>
<p>Is there something that will take any python object and display it in a more rational manner. e.g.</p>
<pre><code>[0, 1,
[a, b, c],
2, 3, 4]
</code></pre>
<p>instead of:</p>
<pre><code>[0, 1, [a, b, c], 2, 3, 4]
</code></pre>
<p>I know that's not a very good example, but I think you get the idea.</p>
| 16 | 2008-09-18T11:43:45Z | 91,972 | <p>Another good option is to use <a href="http://ipython.scipy.org/moin/" rel="nofollow">IPython</a>, which is an interactive environment with a lot of extra features, including automatic pretty printing, tab-completion of methods, easy shell access, and a lot more. It's also very easy to install. </p>
<p><a href="http://ipython.scipy.org/doc/manual/html/interactive/tutorial.html" rel="nofollow">IPython tutorial</a></p>
| 3 | 2008-09-18T12:15:04Z | [
"python",
"prettify"
] |
Is there a pretty printer for python data? | 91,810 | <p>Working with python interactively, it's sometimes necessary to display a result which is some arbitrarily complex data structure (like lists with embedded lists, etc.)
The default way to display them is just one massive linear dump which just wraps over and over and you have to parse carefully to read it.</p>
<p>Is there something that will take any python object and display it in a more rational manner. e.g.</p>
<pre><code>[0, 1,
[a, b, c],
2, 3, 4]
</code></pre>
<p>instead of:</p>
<pre><code>[0, 1, [a, b, c], 2, 3, 4]
</code></pre>
<p>I know that's not a very good example, but I think you get the idea.</p>
| 16 | 2008-09-18T11:43:45Z | 92,260 | <p>Somtimes <a href="http://pyyaml.org/">YAML</a> can be good for this.</p>
<pre><code>import yaml
a = [0, 1, ['a', 'b', 'c'], 2, 3, 4]
print yaml.dump(a)
</code></pre>
<p>Produces:</p>
<pre><code>- 0
- 1
- [a, b, c]
- 2
- 3
- 4
</code></pre>
| 10 | 2008-09-18T12:55:39Z | [
"python",
"prettify"
] |
Is there a pretty printer for python data? | 91,810 | <p>Working with python interactively, it's sometimes necessary to display a result which is some arbitrarily complex data structure (like lists with embedded lists, etc.)
The default way to display them is just one massive linear dump which just wraps over and over and you have to parse carefully to read it.</p>
<p>Is there something that will take any python object and display it in a more rational manner. e.g.</p>
<pre><code>[0, 1,
[a, b, c],
2, 3, 4]
</code></pre>
<p>instead of:</p>
<pre><code>[0, 1, [a, b, c], 2, 3, 4]
</code></pre>
<p>I know that's not a very good example, but I think you get the idea.</p>
| 16 | 2008-09-18T11:43:45Z | 93,312 | <p>In addition to <code>pprint.pprint</code>, <code>pprint.pformat</code> is really useful for making readable <code>__repr__</code>s. My complex <code>__repr__</code>s usually look like so:</p>
<pre><code>def __repr__(self):
from pprint import pformat
return "<ClassName %s>" % pformat({"attrs":self.attrs,
"that_i":self.that_i,
"care_about":self.care_about})
</code></pre>
| 8 | 2008-09-18T14:56:26Z | [
"python",
"prettify"
] |
Google App Engine: how can I programmatically access the properties of my Model class? | 91,821 | <p>I have a model class:</p>
<pre><code>class Person(db.Model):
first_name = db.StringProperty(required=True)
last_name = db.StringProperty(required=True)
</code></pre>
<p>I have an instance of this class in <code>p</code>, and string <code>s</code> contains the value <code>'first_name'</code>. I would like to do something like:</p>
<pre><code>print p[s]
</code></pre>
<p>and </p>
<pre><code>p[s] = new_value
</code></pre>
<p>Both of which result in a <code>TypeError</code>.</p>
<p>Does anybody know how I can achieve what I would like?</p>
| 8 | 2008-09-18T11:45:16Z | 91,859 | <pre><code>getattr(p, s)
setattr(p, s, new_value)
</code></pre>
| 1 | 2008-09-18T11:54:13Z | [
"python",
"string",
"google-app-engine"
] |
Google App Engine: how can I programmatically access the properties of my Model class? | 91,821 | <p>I have a model class:</p>
<pre><code>class Person(db.Model):
first_name = db.StringProperty(required=True)
last_name = db.StringProperty(required=True)
</code></pre>
<p>I have an instance of this class in <code>p</code>, and string <code>s</code> contains the value <code>'first_name'</code>. I would like to do something like:</p>
<pre><code>print p[s]
</code></pre>
<p>and </p>
<pre><code>p[s] = new_value
</code></pre>
<p>Both of which result in a <code>TypeError</code>.</p>
<p>Does anybody know how I can achieve what I would like?</p>
| 8 | 2008-09-18T11:45:16Z | 91,911 | <p>Try:</p>
<pre><code>p.model_properties()[s].get_value_for_datastore(p)
</code></pre>
<p>See <a href="http://code.google.com/appengine/docs/datastore/propertyclass.html#Property_get_value_for_datastore" rel="nofollow">the documentation</a>.</p>
| 1 | 2008-09-18T12:06:25Z | [
"python",
"string",
"google-app-engine"
] |
Google App Engine: how can I programmatically access the properties of my Model class? | 91,821 | <p>I have a model class:</p>
<pre><code>class Person(db.Model):
first_name = db.StringProperty(required=True)
last_name = db.StringProperty(required=True)
</code></pre>
<p>I have an instance of this class in <code>p</code>, and string <code>s</code> contains the value <code>'first_name'</code>. I would like to do something like:</p>
<pre><code>print p[s]
</code></pre>
<p>and </p>
<pre><code>p[s] = new_value
</code></pre>
<p>Both of which result in a <code>TypeError</code>.</p>
<p>Does anybody know how I can achieve what I would like?</p>
| 8 | 2008-09-18T11:45:16Z | 91,970 | <p>If the model class is sufficiently intelligent, it should recognize the standard Python ways of doing this.</p>
<p>Try:</p>
<pre><code>getattr(p, s)
setattr(p, s, new_value)
</code></pre>
<p>There is also hasattr available.</p>
| 7 | 2008-09-18T12:14:37Z | [
"python",
"string",
"google-app-engine"
] |
Google App Engine: how can I programmatically access the properties of my Model class? | 91,821 | <p>I have a model class:</p>
<pre><code>class Person(db.Model):
first_name = db.StringProperty(required=True)
last_name = db.StringProperty(required=True)
</code></pre>
<p>I have an instance of this class in <code>p</code>, and string <code>s</code> contains the value <code>'first_name'</code>. I would like to do something like:</p>
<pre><code>print p[s]
</code></pre>
<p>and </p>
<pre><code>p[s] = new_value
</code></pre>
<p>Both of which result in a <code>TypeError</code>.</p>
<p>Does anybody know how I can achieve what I would like?</p>
| 8 | 2008-09-18T11:45:16Z | 97,760 | <p>With much thanks to Jim, the exact solution I was looking for is:</p>
<pre><code>p.properties()[s].get_value_for_datastore(p)
</code></pre>
<p>To all the other respondents, thank you for your help. I also would have expected the Model class to implement the python standard way of doing this, but for whatever reason, it doesn't.</p>
| 3 | 2008-09-18T22:46:08Z | [
"python",
"string",
"google-app-engine"
] |
Google App Engine: how can I programmatically access the properties of my Model class? | 91,821 | <p>I have a model class:</p>
<pre><code>class Person(db.Model):
first_name = db.StringProperty(required=True)
last_name = db.StringProperty(required=True)
</code></pre>
<p>I have an instance of this class in <code>p</code>, and string <code>s</code> contains the value <code>'first_name'</code>. I would like to do something like:</p>
<pre><code>print p[s]
</code></pre>
<p>and </p>
<pre><code>p[s] = new_value
</code></pre>
<p>Both of which result in a <code>TypeError</code>.</p>
<p>Does anybody know how I can achieve what I would like?</p>
| 8 | 2008-09-18T11:45:16Z | 169,899 | <p>p.first_name = "New first name"
p.put()</p>
<p>or p = Person(first_name = "Firsty",
last_name = "Lasty" )
p.put()</p>
| -1 | 2008-10-04T07:10:55Z | [
"python",
"string",
"google-app-engine"
] |
Python, beyond the basics | 92,230 | <p>I've gotten to grips with the basics of Python and I've got a small holiday which I want to use some of to learn a little more Python. The problem is that I have no idea what to learn or where to start. I'm primarily web development but in this case I don't know how much difference it will make.</p>
| 16 | 2008-09-18T12:51:07Z | 92,254 | <p>I'd suggest writing a non-trivial webapp using either Django or Pylons, something that does some number crunching.
No better way to learn a new language than commiting yourself to a problem and learning as you go!</p>
| 1 | 2008-09-18T12:54:38Z | [
"python"
] |
Python, beyond the basics | 92,230 | <p>I've gotten to grips with the basics of Python and I've got a small holiday which I want to use some of to learn a little more Python. The problem is that I have no idea what to learn or where to start. I'm primarily web development but in this case I don't know how much difference it will make.</p>
| 16 | 2008-09-18T12:51:07Z | 92,269 | <p>Something great to play around with, though not a project, is <a href="http://pythonchallenge.com" rel="nofollow">The Python Challenge</a>. I've found it quite useful in improving my python skills, and it gives your brain a good workout at the same time.</p>
| 3 | 2008-09-18T12:56:33Z | [
"python"
] |
Python, beyond the basics | 92,230 | <p>I've gotten to grips with the basics of Python and I've got a small holiday which I want to use some of to learn a little more Python. The problem is that I have no idea what to learn or where to start. I'm primarily web development but in this case I don't know how much difference it will make.</p>
| 16 | 2008-09-18T12:51:07Z | 92,288 | <p>I honestly loved the book <a href="http://rads.stackoverflow.com/amzn/click/0596009259" rel="nofollow">Programming Python.</a> It has a large assortment of small projects, most of which can be completed in an evening at a leisurely pace. They get you acquainted with most of the standard library and will likely hold your interest. Most importantly these small projects are actually useful in a "day to day" sense. The book pretty much only assumes you know and understand the bare essentials of Python as a language, rather than knowledge of it's huge API library.</p>
<p>I think you'll find it'll be well worth working through.</p>
| 2 | 2008-09-18T12:57:32Z | [
"python"
] |
Python, beyond the basics | 92,230 | <p>I've gotten to grips with the basics of Python and I've got a small holiday which I want to use some of to learn a little more Python. The problem is that I have no idea what to learn or where to start. I'm primarily web development but in this case I don't know how much difference it will make.</p>
| 16 | 2008-09-18T12:51:07Z | 92,296 | <p>Depending on exactly what you mean by "gotten to grips with the basics", I'd suggest reading through <a href="http://www.diveintopython.net/" rel="nofollow">Dive Into Python</a> and typing/executing all the chapter code, then get something like <a href="http://www.amazon.co.uk/Programming-Collective-Intelligence-Building-Applications/dp/0596529325/" rel="nofollow">Programming Collective Intelligence</a> and working through it - you'll learn python quite well, not to mention some quite excellent algorithms that'll come in handy to a web developer.</p>
| 5 | 2008-09-18T12:58:50Z | [
"python"
] |
Python, beyond the basics | 92,230 | <p>I've gotten to grips with the basics of Python and I've got a small holiday which I want to use some of to learn a little more Python. The problem is that I have no idea what to learn or where to start. I'm primarily web development but in this case I don't know how much difference it will make.</p>
| 16 | 2008-09-18T12:51:07Z | 92,318 | <p>Well, there are great ressources for advanced Python programming :</p>
<ul>
<li>Dive Into Python (<a href="http://www.diveintopython.net/">read it for free</a>)</li>
<li>Online python cookbooks (e.g. <a href="http://code.activestate.com/recipes/langs/python/">here</a> and <a href="http://the.taoofmac.com/space/Python/Grimoire">there</a>)</li>
<li>O'Reilly's Python Cookbook (see amazon)</li>
<li>A funny riddle game : <a href="http://www.pythonchallenge.com/">Python Challenge</a> </li>
</ul>
<p>Here is a list of subjects you must master if you want to write "Python" on your resume :</p>
<ul>
<li><a href="http://docs.python.org/tutorial/datastructures.html#list-comprehensions">list comprehensions</a></li>
<li><a href="http://stackoverflow.com/questions/231767/the-python-yield-keyword-explained/231855#231855">iterators and generators</a></li>
<li><a href="http://stackoverflow.com/questions/739654/understanding-python-decorators/1594484#1594484">decorators</a></li>
</ul>
<p>They are what make Python such a cool language (with the standard library of course, that I keep discovering everyday).</p>
| 14 | 2008-09-18T13:01:53Z | [
"python"
] |
Python, beyond the basics | 92,230 | <p>I've gotten to grips with the basics of Python and I've got a small holiday which I want to use some of to learn a little more Python. The problem is that I have no idea what to learn or where to start. I'm primarily web development but in this case I don't know how much difference it will make.</p>
| 16 | 2008-09-18T12:51:07Z | 92,381 | <p>Write a web app, likely in <a href="http://www.djangoproject.com/" rel="nofollow">Django</a> - the <a href="http://docs.djangoproject.com/" rel="nofollow">docs</a> will teach you a lot of good Python style.</p>
<p>Use some of the popular libraries like <a href="http://pygments.org/" rel="nofollow">Pygments</a> or the <a href="http://www.feedparser.org/" rel="nofollow">Universal Feed Parser</a>. Both of these make extremely useful functions, which are hard to get right, available in a well-documented API.</p>
<p>In general, I'd stay away from libs that aren't well documented -
you'll bang your head on the wall trying to reverse-engineer them -
and libraries that are wrappers around C libraries, if you don't have
any C experience. I worked on wxPython code when I was still learning
Python, which was my first language, and at the time it was little
more than a wrapper around wxWidgets. That code was easily the ugliest
I've ever written.</p>
<p>I didn't get that much out of Dive Into Python, except for the dynamic import chapter - that's not really well-documented elsewhere.</p>
| 1 | 2008-09-18T13:10:07Z | [
"python"
] |
Python, beyond the basics | 92,230 | <p>I've gotten to grips with the basics of Python and I've got a small holiday which I want to use some of to learn a little more Python. The problem is that I have no idea what to learn or where to start. I'm primarily web development but in this case I don't know how much difference it will make.</p>
| 16 | 2008-09-18T12:51:07Z | 92,461 | <p>People tend to say something along the lines of "The best way to learn is by doing" but I've always found that unless you're specifically learning a language to contribute to some project it's difficult to actually find little problems to tackle to keep yourself going.</p>
<p>A good solution to this is <a href="http://projecteuler.net/" rel="nofollow">Project Euler</a>, which has a list of various programming\mathematics challenges ranging from simple to quite brain-taxing. As an example, the first challenge is:</p>
<blockquote>
<p>If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.</p>
</blockquote>
<p>And by problem #50 it's already getting a little tougher</p>
<blockquote>
<p>Which prime, below one-million, can be written as the sum of the most consecutive primes</p>
</blockquote>
<p>There are 208 in total, but I think some new ones get added here and there.</p>
<p>While I already knew python fairly well before starting Project Euler, I found that I learned some cool tricks purely through using the language so much. Good luck!</p>
| 1 | 2008-09-18T13:20:21Z | [
"python"
] |
Python, beyond the basics | 92,230 | <p>I've gotten to grips with the basics of Python and I've got a small holiday which I want to use some of to learn a little more Python. The problem is that I have no idea what to learn or where to start. I'm primarily web development but in this case I don't know how much difference it will make.</p>
| 16 | 2008-09-18T12:51:07Z | 92,491 | <p>I'll plug <a href="http://homepage.mac.com/s_lott/books/python.html" rel="nofollow">Building Skills in Python</a>. Plus, if you want something more challenging, <a href="http://homepage.mac.com/s_lott/books/oodesign.html" rel="nofollow">Building Skills in OO Design</a> is a rather large and complex series of exercises.</p>
| 2 | 2008-09-18T13:23:41Z | [
"python"
] |
Python, beyond the basics | 92,230 | <p>I've gotten to grips with the basics of Python and I've got a small holiday which I want to use some of to learn a little more Python. The problem is that I have no idea what to learn or where to start. I'm primarily web development but in this case I don't know how much difference it will make.</p>
| 16 | 2008-09-18T12:51:07Z | 92,691 | <p><em>The Python Cookbook</em> is absolutely essential if you want to master idiomatic Python. Besides, that's the book that made me fall in love with the language.</p>
| 2 | 2008-09-18T13:49:59Z | [
"python"
] |
Python, beyond the basics | 92,230 | <p>I've gotten to grips with the basics of Python and I've got a small holiday which I want to use some of to learn a little more Python. The problem is that I have no idea what to learn or where to start. I'm primarily web development but in this case I don't know how much difference it will make.</p>
| 16 | 2008-09-18T12:51:07Z | 181,078 | <p>Search "Alex Martelli", "Alex Martelli patterns" and "Thomas Wouters" on Google video. There's plenty of interesting talks on andvanced Python, design patterns in Python, and so on.</p>
| 1 | 2008-10-08T01:31:46Z | [
"python"
] |
Django + FCGID on Fedora Core 9 -- what am I missing? | 92,373 | <p>Fedora Core 9 seems to have <a href="http://fastcgi.coremail.cn/" rel="nofollow">FCGID</a> instead of <a href="http://www.fastcgi.com/drupal/node/2" rel="nofollow">FastCGI</a> as a pre-built, YUM-managed module. [<em>I'd rather not have to maintain a module outside of YUM; so no manual builds for me or my sysadmins.</em>]</p>
<p>I'm trying to launch Django through the runfastcgi interface (per the <a href="http://docs.djangoproject.com/en/dev/howto/deployment/fastcgi/" rel="nofollow">FastCGI deployment</a> docs). </p>
<p>What I'm seeing is the resulting page written to <code>error_log</code>. It does not come back through Apache to my browser. Further, there are a bunch of messages -- apparently from <a href="http://trac.saddi.com/flup" rel="nofollow">flup</a> and WSGIServer -- that indicate that the WSGI environment isn't defined properly.</p>
<ol>
<li><p>Is FastCGI available for FC9, and I just overlooked it?</p></li>
<li><p>Does FCGID and flup actually create the necessary WSGI environment for Django? If so, can you share the <code>.fcgi</code> interface script you're using? Mine is copied from <code>mysite.fcgi </code> in the Django docs. The FCGID <a href="http://fastcgi.coremail.cn/doc.htm" rel="nofollow">Documentations</a> page drops hints that PHP and Ruby are supported -- PHP directly, and Ruby through <code>dispatch.fcgi</code> -- and Python is not supported.</p></li>
</ol>
<p><strong>Update</strong>. The error messages are...</p>
<pre><code>WSGIServer: missing FastCGI param REQUEST_METHOD required by WSGI!
WSGIServer: missing FastCGI param SERVER_NAME required by WSGI!
WSGIServer: missing FastCGI param SERVER_PORT required by WSGI!
WSGIServer: missing FastCGI param SERVER_PROTOCOL required by WSGI!
</code></pre>
<p>Should I abandon ship and switch to <a href="http://www.modpython.org/" rel="nofollow">mod_python</a> and give up on this approach?</p>
| 0 | 2008-09-18T13:09:21Z | 92,891 | <p>Why don't you try <a href="http://code.google.com/p/modwsgi/" rel="nofollow">modwsgi</a>? It sounds as the preffered way these days for WSGI applications such as Django.</p>
<p>If you don't wan't to compile stuff for Fedora Core, that might be trickier.</p>
<p>Regarding 1) <a href="http://fitri.manzanisimo.net/2008/05/23/hostmonster-python-25-subversion-14-django-svn-mysqldb-fcgid/" rel="nofollow">this</a> seems to solve the fcgid configuration problem. </p>
<p>Note that you don't want to run the django application manually like this: <code>python manage.py runfcgi</code>, the fcgi is run by apache automatically if the setup is correct and restarted by <code>touch your.fcgi</code>.</p>
| 1 | 2008-09-18T14:13:09Z | [
"python",
"django",
"apache2",
"fastcgi",
"fcgid"
] |
Stripping non printable characters from a string in python | 92,438 | <p>I use to run</p>
<pre><code>$s =~ s/[^[:print:]]//g;
</code></pre>
<p>on Perl to get rid of non printable characters. </p>
<p>In Python there's no POSIX regex classes, and I can't write [:print:] having it mean what I want. I know of no way in Python to detect if a character is printable or not. </p>
<p>What would you do? </p>
<p>EDIT: It has to support Unicode characters as well. The string.printable way will happily strip them out of the output.
curses.ascii.isprint will return false for any unicode character.</p>
| 59 | 2008-09-18T13:17:06Z | 92,441 | <p>The best I've come up with now is (thanks to the python-izers above) </p>
<pre><code>def filter_non_printable(str):
return ''.join([c for c in str if ord(c) > 31 or ord(c) == 9])
</code></pre>
<p>This is the only way I've found out that works with Unicode characters/strings</p>
<p>Any better options?</p>
| 0 | 2008-09-18T13:17:35Z | [
"python",
"string",
"non-printable"
] |
Stripping non printable characters from a string in python | 92,438 | <p>I use to run</p>
<pre><code>$s =~ s/[^[:print:]]//g;
</code></pre>
<p>on Perl to get rid of non printable characters. </p>
<p>In Python there's no POSIX regex classes, and I can't write [:print:] having it mean what I want. I know of no way in Python to detect if a character is printable or not. </p>
<p>What would you do? </p>
<p>EDIT: It has to support Unicode characters as well. The string.printable way will happily strip them out of the output.
curses.ascii.isprint will return false for any unicode character.</p>
| 59 | 2008-09-18T13:17:06Z | 92,488 | <p>As far as I know, the most pythonic/efficient method would be:</p>
<pre><code>import string
filtered_string = filter(lambda x: x in string.printable, myStr)
</code></pre>
| 38 | 2008-09-18T13:23:14Z | [
"python",
"string",
"non-printable"
] |
Stripping non printable characters from a string in python | 92,438 | <p>I use to run</p>
<pre><code>$s =~ s/[^[:print:]]//g;
</code></pre>
<p>on Perl to get rid of non printable characters. </p>
<p>In Python there's no POSIX regex classes, and I can't write [:print:] having it mean what I want. I know of no way in Python to detect if a character is printable or not. </p>
<p>What would you do? </p>
<p>EDIT: It has to support Unicode characters as well. The string.printable way will happily strip them out of the output.
curses.ascii.isprint will return false for any unicode character.</p>
| 59 | 2008-09-18T13:17:06Z | 92,509 | <p>This function uses list comprehensions and str.join, so it runs in linear time instead of O(n^2):</p>
<pre><code>from curses.ascii import isprint
def printable(input):
return ''.join(char for char in input if isprint(char))
</code></pre>
| 4 | 2008-09-18T13:26:00Z | [
"python",
"string",
"non-printable"
] |
Stripping non printable characters from a string in python | 92,438 | <p>I use to run</p>
<pre><code>$s =~ s/[^[:print:]]//g;
</code></pre>
<p>on Perl to get rid of non printable characters. </p>
<p>In Python there's no POSIX regex classes, and I can't write [:print:] having it mean what I want. I know of no way in Python to detect if a character is printable or not. </p>
<p>What would you do? </p>
<p>EDIT: It has to support Unicode characters as well. The string.printable way will happily strip them out of the output.
curses.ascii.isprint will return false for any unicode character.</p>
| 59 | 2008-09-18T13:17:06Z | 93,029 | <p>Iterating over strings is unfortunately rather slow in Python. Regular expressions are over an order of magnitude faster for this kind of thing. You just have to build the character class yourself. The <em>unicodedata</em> module is quite helpful for this, especially the <em>unicodedata.category()</em> function. See <a href="http://www.unicode.org/reports/tr44/#General_Category_Values">Unicode Character Database</a> for descriptions of the categories.</p>
<pre><code>import unicodedata, re
all_chars = (unichr(i) for i in xrange(0x110000))
control_chars = ''.join(c for c in all_chars if unicodedata.category(c) == 'Cc')
# or equivalently and much more efficiently
control_chars = ''.join(map(unichr, range(0,32) + range(127,160)))
control_char_re = re.compile('[%s]' % re.escape(control_chars))
def remove_control_chars(s):
return control_char_re.sub('', s)
</code></pre>
| 52 | 2008-09-18T14:28:04Z | [
"python",
"string",
"non-printable"
] |
Stripping non printable characters from a string in python | 92,438 | <p>I use to run</p>
<pre><code>$s =~ s/[^[:print:]]//g;
</code></pre>
<p>on Perl to get rid of non printable characters. </p>
<p>In Python there's no POSIX regex classes, and I can't write [:print:] having it mean what I want. I know of no way in Python to detect if a character is printable or not. </p>
<p>What would you do? </p>
<p>EDIT: It has to support Unicode characters as well. The string.printable way will happily strip them out of the output.
curses.ascii.isprint will return false for any unicode character.</p>
| 59 | 2008-09-18T13:17:06Z | 93,557 | <p>You could try setting up a filter using the <code>unicodedata.category()</code> function:</p>
<pre><code>printable = Set('Lu', 'Ll', ...)
def filter_non_printable(str):
return ''.join(c for c in str if unicodedata.category(c) in printable)
</code></pre>
<p>See the <a href="http://www.unicode.org/versions/Unicode9.0.0/ch04.pdf" rel="nofollow">Unicode database character properties</a> for the available categories</p>
| 8 | 2008-09-18T15:25:37Z | [
"python",
"string",
"non-printable"
] |
Stripping non printable characters from a string in python | 92,438 | <p>I use to run</p>
<pre><code>$s =~ s/[^[:print:]]//g;
</code></pre>
<p>on Perl to get rid of non printable characters. </p>
<p>In Python there's no POSIX regex classes, and I can't write [:print:] having it mean what I want. I know of no way in Python to detect if a character is printable or not. </p>
<p>What would you do? </p>
<p>EDIT: It has to support Unicode characters as well. The string.printable way will happily strip them out of the output.
curses.ascii.isprint will return false for any unicode character.</p>
| 59 | 2008-09-18T13:17:06Z | 25,829,509 | <p>In Python 3,</p>
<pre><code>def filter_nonprintable(text):
import string
# Get the difference of all ASCII characters from the set of printable characters
nonprintable = set([chr(i) for i in range(128)]).difference(string.printable)
# Use translate to remove all non-printable characters
return text.translate({ord(character):None for character in nonprintable})
</code></pre>
<p>See <a href="http://stackoverflow.com/questions/265960/best-way-to-strip-punctuation-from-a-string-in-python">this StackOverflow post on removing punctuation</a> for how .translate() compares to regex & .replace()</p>
| 3 | 2014-09-14T02:20:39Z | [
"python",
"string",
"non-printable"
] |
Python module functions used in unexpected ways | 92,533 | <p>Based on <a href="http://stackoverflow.com/questions/6209/split-a-string-ignoring-quoted-sections#6243">"Split a string by spaces in Python"</a>, which uses <em>shlex.split</em> to split a string with quotes smartly, I would be interested in hearing about other common tasks solved by non-obvious standard library functions. </p>
<p>If this turns into <a href="http://www.doughellmann.com/projects/PyMOTW/" rel="nofollow">Module of The Week</a>, that's fine too. </p>
| 4 | 2008-09-18T13:29:56Z | 92,548 | <p>I found struct.unpack to be a godsend for unpacking binary data formats after I learned of it!</p>
| 2 | 2008-09-18T13:32:23Z | [
"python"
] |
Python module functions used in unexpected ways | 92,533 | <p>Based on <a href="http://stackoverflow.com/questions/6209/split-a-string-ignoring-quoted-sections#6243">"Split a string by spaces in Python"</a>, which uses <em>shlex.split</em> to split a string with quotes smartly, I would be interested in hearing about other common tasks solved by non-obvious standard library functions. </p>
<p>If this turns into <a href="http://www.doughellmann.com/projects/PyMOTW/" rel="nofollow">Module of The Week</a>, that's fine too. </p>
| 4 | 2008-09-18T13:29:56Z | 93,498 | <p>I've found <a href="http://docs.python.org/lib/module-sched.html" rel="nofollow">sched module</a> to be helpful in cron-like activities. It simplifies things a lot. Unfortunately I found it too late. </p>
| 1 | 2008-09-18T15:17:34Z | [
"python"
] |
Python module functions used in unexpected ways | 92,533 | <p>Based on <a href="http://stackoverflow.com/questions/6209/split-a-string-ignoring-quoted-sections#6243">"Split a string by spaces in Python"</a>, which uses <em>shlex.split</em> to split a string with quotes smartly, I would be interested in hearing about other common tasks solved by non-obvious standard library functions. </p>
<p>If this turns into <a href="http://www.doughellmann.com/projects/PyMOTW/" rel="nofollow">Module of The Week</a>, that's fine too. </p>
| 4 | 2008-09-18T13:29:56Z | 93,865 | <p>Oft overlooked modules, uses and tricks:</p>
<p>collections.defaultdict(): for when you want missing keys in a dict to have a default value.</p>
<p>functools.wraps(): for writing decorators that play nicely with introspection.</p>
<p>posixpath: the os.path module for POSIX systems. You can use it for manipulating POSIX paths (including URI elements) even on Windows and other non-POSIX systems.</p>
<p>ntpath: the os.path module for Windows; usable for manipulation of Windows paths on non-Windows systems.</p>
<p>(also: macpath, for MacOS 9 and earlier, os2emxpath for OS/2 EMX, but I'm not sure if anyone still cares.)</p>
<p>pprint: more structured printing of the repr() of containers makes debugging much easier.</p>
<p>imp: all the tools you need to write your own plugin system or make Python import modules from arbitrary archives.</p>
<p>rlcompleter: getting tab-completion in the normal interactive interpreter. Just do "import readline, rlcompleter; readline.parse_and_bind('tab: complete')"</p>
<p>the PYTHONSTARTUP environment variable: can be set to the path to a file that will be executed (in the main namespace) when entering the interactive interpreter; useful for putting things in like the rlcompleter recipe above.</p>
| 4 | 2008-09-18T15:56:57Z | [
"python"
] |
Python module functions used in unexpected ways | 92,533 | <p>Based on <a href="http://stackoverflow.com/questions/6209/split-a-string-ignoring-quoted-sections#6243">"Split a string by spaces in Python"</a>, which uses <em>shlex.split</em> to split a string with quotes smartly, I would be interested in hearing about other common tasks solved by non-obvious standard library functions. </p>
<p>If this turns into <a href="http://www.doughellmann.com/projects/PyMOTW/" rel="nofollow">Module of The Week</a>, that's fine too. </p>
| 4 | 2008-09-18T13:29:56Z | 94,551 | <p><a href="http://docs.python.org/lib/module-getpass.html" rel="nofollow">getpass</a> is useful for determining the login name of the current user.</p>
<p><a href="http://docs.python.org/lib/module-grp.html" rel="nofollow">grp</a> allows you to lookup Unix group IDs by name, and vice versa.</p>
<p><a href="http://docs.python.org/lib/module-dircache.html" rel="nofollow">dircache</a> might be useful in situations where you're repeatedly polling the contents of a directory.</p>
<p><a href="http://docs.python.org/lib/module-glob.html" rel="nofollow">glob</a> can find filenames matching wildcards like a Unix shell does.</p>
<p><a href="http://docs.python.org/lib/module-shutil.html" rel="nofollow">shutil</a> is useful when you need to copy, delete or rename a file.</p>
<p><a href="http://docs.python.org/lib/module-csv.html" rel="nofollow">csv</a> can simplify parsing of delimited text files.</p>
<p><a href="http://docs.python.org/lib/module-optparse.html" rel="nofollow">optparse</a> provides a reliable way to parse command line options.</p>
<p><a href="http://docs.python.org/lib/module-bz2.html" rel="nofollow">bz2</a> comes in handy when you need to manipulate a bzip2-compressed file.</p>
<p><a href="http://docs.python.org/lib/module-urlparse.html" rel="nofollow">urlparse</a> will save you the hassle of breaking up a URL into component parts.</p>
| 2 | 2008-09-18T17:11:53Z | [
"python"
] |
Python module functions used in unexpected ways | 92,533 | <p>Based on <a href="http://stackoverflow.com/questions/6209/split-a-string-ignoring-quoted-sections#6243">"Split a string by spaces in Python"</a>, which uses <em>shlex.split</em> to split a string with quotes smartly, I would be interested in hearing about other common tasks solved by non-obvious standard library functions. </p>
<p>If this turns into <a href="http://www.doughellmann.com/projects/PyMOTW/" rel="nofollow">Module of The Week</a>, that's fine too. </p>
| 4 | 2008-09-18T13:29:56Z | 94,991 | <p>Most of the other examples are merely overlooked, not unexpected uses for module.</p>
<p>fnmatch, like shlex, can be applied in unexpected ways. fnmatch is a kind of poor-person's RE, and can be used for more than matching files, it can compare strings with the simplified wild-card patterns.</p>
| 1 | 2008-09-18T17:58:06Z | [
"python"
] |
Python module functions used in unexpected ways | 92,533 | <p>Based on <a href="http://stackoverflow.com/questions/6209/split-a-string-ignoring-quoted-sections#6243">"Split a string by spaces in Python"</a>, which uses <em>shlex.split</em> to split a string with quotes smartly, I would be interested in hearing about other common tasks solved by non-obvious standard library functions. </p>
<p>If this turns into <a href="http://www.doughellmann.com/projects/PyMOTW/" rel="nofollow">Module of The Week</a>, that's fine too. </p>
| 4 | 2008-09-18T13:29:56Z | 95,159 | <p>I use itertools (especially cycle, repeat, chain) to make python behave more like R and in other functional / vector applications. Often this lets me avoid the overhead and complication of Numpy. </p>
<pre><code># in R, shorter iterables are automatically cycled
# and all functions "apply" in a "map"-like way over lists
> 0:10 + 0:2
[1] 0 2 4 3 5 7 6 8 10 9 11
</code></pre>
<p>Python
#Normal python
In [1]: range(10) + range(3)
Out[1]: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2]</p>
<pre><code>## this code is terrible, but it demos the idea.
from itertools import cycle
def addR(L1,L2):
n = max( len(L1), len(L2))
out = [None,]*n
gen1,gen2 = cycle(L1), cycle(L2)
ii = 0
while ii < n:
out[ii] = gen1.next() + gen2.next()
ii += 1
return out
In [21]: addR(range(10), range(3))
Out[21]: [0, 2, 4, 3, 5, 7, 6, 8, 10, 9]
</code></pre>
| 3 | 2008-09-18T18:13:28Z | [
"python"
] |
Python module functions used in unexpected ways | 92,533 | <p>Based on <a href="http://stackoverflow.com/questions/6209/split-a-string-ignoring-quoted-sections#6243">"Split a string by spaces in Python"</a>, which uses <em>shlex.split</em> to split a string with quotes smartly, I would be interested in hearing about other common tasks solved by non-obvious standard library functions. </p>
<p>If this turns into <a href="http://www.doughellmann.com/projects/PyMOTW/" rel="nofollow">Module of The Week</a>, that's fine too. </p>
| 4 | 2008-09-18T13:29:56Z | 95,825 | <p>I was quite surprised to learn that you could use the bisect module to do a very fast binary search in a sequence. It's documentation doesn't say anything about it:</p>
<blockquote>
<p>This module provides support for maintaining a list in sorted order without having to sort the list after each insertion.</p>
</blockquote>
<p>The usage is very simple:</p>
<pre><code>>>> import bisect
>>> lst = [4, 7, 10, 23, 25, 100, 103, 201, 333]
>>> bisect.bisect_left(lst, 23)
3
</code></pre>
<p>You have to remember though, that it's quicker to linearly look for something in a list goes item by item, than sorting the list and then doing a binary search on it. The first option is O(n), the second is O(nlogn).</p>
| 6 | 2008-09-18T19:08:34Z | [
"python"
] |
Python module functions used in unexpected ways | 92,533 | <p>Based on <a href="http://stackoverflow.com/questions/6209/split-a-string-ignoring-quoted-sections#6243">"Split a string by spaces in Python"</a>, which uses <em>shlex.split</em> to split a string with quotes smartly, I would be interested in hearing about other common tasks solved by non-obvious standard library functions. </p>
<p>If this turns into <a href="http://www.doughellmann.com/projects/PyMOTW/" rel="nofollow">Module of The Week</a>, that's fine too. </p>
| 4 | 2008-09-18T13:29:56Z | 97,103 | <p>One function I've come to appreciate is string.translate. Its very fast at what it does, and useful anywhere you want to alter or remove characters in a string. I've just used it in a seemingly inapplicable <a href="http://stackoverflow.com/questions/89909/in-python-how-to-i-verify-that-a-string-only-contains-letters-numbers-underscor#92000">problem</a> and found it beat all the other solutions handily.</p>
<p>The downside is that its API is a bit clunky, but this is improving in Py2.6 / Py3.0.</p>
| 1 | 2008-09-18T21:20:29Z | [
"python"
] |
Python module functions used in unexpected ways | 92,533 | <p>Based on <a href="http://stackoverflow.com/questions/6209/split-a-string-ignoring-quoted-sections#6243">"Split a string by spaces in Python"</a>, which uses <em>shlex.split</em> to split a string with quotes smartly, I would be interested in hearing about other common tasks solved by non-obvious standard library functions. </p>
<p>If this turns into <a href="http://www.doughellmann.com/projects/PyMOTW/" rel="nofollow">Module of The Week</a>, that's fine too. </p>
| 4 | 2008-09-18T13:29:56Z | 99,969 | <p>The <a href="http://docs.python.org/lib/module-pickle.html" rel="nofollow">pickle</a> module is pretty awesome</p>
| 1 | 2008-09-19T05:54:22Z | [
"python"
] |
Python module functions used in unexpected ways | 92,533 | <p>Based on <a href="http://stackoverflow.com/questions/6209/split-a-string-ignoring-quoted-sections#6243">"Split a string by spaces in Python"</a>, which uses <em>shlex.split</em> to split a string with quotes smartly, I would be interested in hearing about other common tasks solved by non-obvious standard library functions. </p>
<p>If this turns into <a href="http://www.doughellmann.com/projects/PyMOTW/" rel="nofollow">Module of The Week</a>, that's fine too. </p>
| 4 | 2008-09-18T13:29:56Z | 101,353 | <p>complex numbers. (The complexobject.c defines a class, so technically it's not a module). Great for 2d coordinates, with easy translation/rotations etc</p>
<p>eg.</p>
<pre><code>TURN_LEFT_90= 1j
TURN_RIGHT_90= -1j
coord= 5+4j # x=5 y=4
print coord*TURN_LEFT_90
</code></pre>
| 1 | 2008-09-19T12:10:20Z | [
"python"
] |
How can I highlight text in Scintilla? | 92,565 | <p>I am writing an editor using <a href="http://www.scintilla.org/" rel="nofollow">Scintilla</a>.</p>
<p>I am already using a lexer to do automatic syntax highlighting but now I would like to mark search results. If I want to mark only one hit I can set the selection there, however, I would like to mark (e.g. with yellow background) all the hits.</p>
<p>I writing this in Perl but if you have suggestions in other languages that would be cool as well.</p>
| 6 | 2008-09-18T13:34:54Z | 92,682 | <p>The "sample" editor scite uses the bookmark feature to bookmark all the lines that match the search result.</p>
| 2 | 2008-09-18T13:48:41Z | [
"c#",
"python",
"perl",
"ide",
"scintilla"
] |
How can I highlight text in Scintilla? | 92,565 | <p>I am writing an editor using <a href="http://www.scintilla.org/" rel="nofollow">Scintilla</a>.</p>
<p>I am already using a lexer to do automatic syntax highlighting but now I would like to mark search results. If I want to mark only one hit I can set the selection there, however, I would like to mark (e.g. with yellow background) all the hits.</p>
<p>I writing this in Perl but if you have suggestions in other languages that would be cool as well.</p>
| 6 | 2008-09-18T13:34:54Z | 92,778 | <p>Have you read the <a href="http://scintilla.sourceforge.net/ScintillaDoc.html#Markers">Markers reference in Scintilla doc</a>?
This reference can be a bit obscure, so I advise to take a look at the source code of SciTE as well. This text editor was originally a testbed for Scintilla. It grown to a full fledged editor, but it is still a good implementation reference for all things Scintilla.</p>
<p>In our particular case, there is a Mark All button in the Find dialog. You can find its implementation in SciTEBase::MarkAll() method. This method only loops on search results (until it loops on the first search result, if any) and puts a bookmark on the found lines (and optionally set an indicator on the found items).
The found line is gotten using SCI_LINEFROMPOSITION(posFound), the bookmark is just a call to SCI_MARKERADD(lineno, markerBookmark).
Note that the mark can be symbol in a margin, or if not associated to a margin, it will highlight the whole line.</p>
<p>HTH.</p>
| 9 | 2008-09-18T13:59:19Z | [
"c#",
"python",
"perl",
"ide",
"scintilla"
] |
How can I highlight text in Scintilla? | 92,565 | <p>I am writing an editor using <a href="http://www.scintilla.org/" rel="nofollow">Scintilla</a>.</p>
<p>I am already using a lexer to do automatic syntax highlighting but now I would like to mark search results. If I want to mark only one hit I can set the selection there, however, I would like to mark (e.g. with yellow background) all the hits.</p>
<p>I writing this in Perl but if you have suggestions in other languages that would be cool as well.</p>
| 6 | 2008-09-18T13:34:54Z | 4,854,367 | <p>I used <a href="http://www.scintilla.org/ScintillaDoc.html#Indicators" rel="nofollow">Indicators</a> to highlight search results.</p>
| 1 | 2011-01-31T18:05:43Z | [
"c#",
"python",
"perl",
"ide",
"scintilla"
] |
Python sockets suddenly timing out? | 92,620 | <p>I came back today to an old script I had for logging into Gmail via SSL. The script worked fine last time I ran it (several months ago) but now it dies immediately with:</p>
<pre><code><urlopen error The read operation timed out>
</code></pre>
<p>If I set the timeout (no matter how long), it dies even more immediately with:</p>
<pre><code><urlopen error The connect operation timed out>
</code></pre>
<p>The latter is reproducible with:</p>
<pre><code>import socket
socket.setdefaulttimeout(30000)
sock = socket.socket()
sock.connect(('www.google.com', 443))
ssl = socket.ssl(sock)
</code></pre>
<p>returning:</p>
<pre><code>socket.sslerror: The connect operation timed out
</code></pre>
<p>but I can't seem to reproduce the former and, after much stepping thru the code, I have no clue what's causing any of this.</p>
| 13 | 2008-09-18T13:41:22Z | 93,401 | <p>www.google.com is not accessible by HTTPS. It redirects to insecure HTTP. To get to mail, you should be going go https://mail.google.com</p>
| 0 | 2008-09-18T15:06:11Z | [
"python",
"api",
"sockets",
"ssl",
"gmail"
] |
Python sockets suddenly timing out? | 92,620 | <p>I came back today to an old script I had for logging into Gmail via SSL. The script worked fine last time I ran it (several months ago) but now it dies immediately with:</p>
<pre><code><urlopen error The read operation timed out>
</code></pre>
<p>If I set the timeout (no matter how long), it dies even more immediately with:</p>
<pre><code><urlopen error The connect operation timed out>
</code></pre>
<p>The latter is reproducible with:</p>
<pre><code>import socket
socket.setdefaulttimeout(30000)
sock = socket.socket()
sock.connect(('www.google.com', 443))
ssl = socket.ssl(sock)
</code></pre>
<p>returning:</p>
<pre><code>socket.sslerror: The connect operation timed out
</code></pre>
<p>but I can't seem to reproduce the former and, after much stepping thru the code, I have no clue what's causing any of this.</p>
| 13 | 2008-09-18T13:41:22Z | 93,404 | <pre><code>import socket
socket.setdefaulttimeout(30000)
sock = socket.socket()
sock.connect(('www.google.com', 443))
ssl = socket.ssl(sock)
ssl.server()
--> '/C=US/ST=California/L=Mountain View/O=Google Inc/CN=www.google.com'
</code></pre>
<p>It works just fine. I can't reproduce your error.</p>
| 1 | 2008-09-18T15:06:36Z | [
"python",
"api",
"sockets",
"ssl",
"gmail"
] |
Python sockets suddenly timing out? | 92,620 | <p>I came back today to an old script I had for logging into Gmail via SSL. The script worked fine last time I ran it (several months ago) but now it dies immediately with:</p>
<pre><code><urlopen error The read operation timed out>
</code></pre>
<p>If I set the timeout (no matter how long), it dies even more immediately with:</p>
<pre><code><urlopen error The connect operation timed out>
</code></pre>
<p>The latter is reproducible with:</p>
<pre><code>import socket
socket.setdefaulttimeout(30000)
sock = socket.socket()
sock.connect(('www.google.com', 443))
ssl = socket.ssl(sock)
</code></pre>
<p>returning:</p>
<pre><code>socket.sslerror: The connect operation timed out
</code></pre>
<p>but I can't seem to reproduce the former and, after much stepping thru the code, I have no clue what's causing any of this.</p>
| 13 | 2008-09-18T13:41:22Z | 96,565 | <p>The first thing I would check is whether you need to connect via an HTTP proxy (in which case direct connections bypassing the proxy will likely time out). Run Wireshark and see what happens.</p>
| 0 | 2008-09-18T20:29:34Z | [
"python",
"api",
"sockets",
"ssl",
"gmail"
] |
time.sleep -- sleeps thread or process? | 92,928 | <p>In Python for the *nix, does <code>time.sleep()</code> block the thread or the process?</p>
| 227 | 2008-09-18T14:16:45Z | 92,953 | <p>Just the thread.</p>
| 15 | 2008-09-18T14:18:51Z | [
"python",
"multithreading",
"time",
"sleep",
"python-internals"
] |
time.sleep -- sleeps thread or process? | 92,928 | <p>In Python for the *nix, does <code>time.sleep()</code> block the thread or the process?</p>
| 227 | 2008-09-18T14:16:45Z | 92,986 | <p>It will just sleep the thread except in the case where your application has only a single thread, in which case it will sleep the thread and effectively the process as well.</p>
<p>The python documentation on sleep doesn't specify this however, so I can certainly understand the confusion!</p>
<p><a href="http://docs.python.org/2/library/time.html">http://docs.python.org/2/library/time.html</a></p>
| 34 | 2008-09-18T14:22:52Z | [
"python",
"multithreading",
"time",
"sleep",
"python-internals"
] |
time.sleep -- sleeps thread or process? | 92,928 | <p>In Python for the *nix, does <code>time.sleep()</code> block the thread or the process?</p>
| 227 | 2008-09-18T14:16:45Z | 93,069 | <p>The thread will block, but the process is still alive.</p>
<p>In a single threaded application, this means everything is blocked while you sleep. In a multithreaded application, only the thread you explicitly 'sleep' will block and the other threads still run within the process.</p>
| 6 | 2008-09-18T14:32:45Z | [
"python",
"multithreading",
"time",
"sleep",
"python-internals"
] |
time.sleep -- sleeps thread or process? | 92,928 | <p>In Python for the *nix, does <code>time.sleep()</code> block the thread or the process?</p>
| 227 | 2008-09-18T14:16:45Z | 93,179 | <p>It blocks the thread. If you look in Modules/timemodule.c in the Python source, you'll see that in the call to <code>floatsleep()</code>, the substantive part of the sleep operation is wrapped in a Py_BEGIN_ALLOW_THREADS and Py_END_ALLOW_THREADS block, allowing other threads to continue to execute while the current one sleeps. You can also test this with a simple python program:</p>
<pre><code>import time
from threading import Thread
class worker(Thread):
def run(self):
for x in xrange(0,11):
print x
time.sleep(1)
class waiter(Thread):
def run(self):
for x in xrange(100,103):
print x
time.sleep(5)
def run():
worker().start()
waiter().start()
</code></pre>
<p>Which will print:</p>
<pre><code>>>> thread_test.run()
0
100
>>> 1
2
3
4
5
101
6
7
8
9
10
102
</code></pre>
| 219 | 2008-09-18T14:42:23Z | [
"python",
"multithreading",
"time",
"sleep",
"python-internals"
] |
time.sleep -- sleeps thread or process? | 92,928 | <p>In Python for the *nix, does <code>time.sleep()</code> block the thread or the process?</p>
| 227 | 2008-09-18T14:16:45Z | 32,216,136 | <p>Only the thread unless your process has a single thread.</p>
| 1 | 2015-08-26T00:21:35Z | [
"python",
"multithreading",
"time",
"sleep",
"python-internals"
] |
What's the easiest non-memory intensive way to output XML from Python? | 93,710 | <p>Basically, something similar to System.Xml.XmlWriter - A streaming XML Writer that doesn't incur much of a memory overhead. So that rules out xml.dom and xml.dom.minidom. Suggestions?</p>
| 12 | 2008-09-18T15:42:19Z | 93,831 | <p>I think I have your poison :</p>
<p><a href="http://sourceforge.net/projects/xmlite" rel="nofollow">http://sourceforge.net/projects/xmlite</a></p>
<p>Cheers</p>
| 1 | 2008-09-18T15:54:07Z | [
"python",
"xml",
"streaming"
] |
What's the easiest non-memory intensive way to output XML from Python? | 93,710 | <p>Basically, something similar to System.Xml.XmlWriter - A streaming XML Writer that doesn't incur much of a memory overhead. So that rules out xml.dom and xml.dom.minidom. Suggestions?</p>
| 12 | 2008-09-18T15:42:19Z | 93,850 | <p><strong>xml.etree.cElementTree</strong>, included in the default distribution of CPython since 2.5. Lightning fast for both reading and writing XML.</p>
| -4 | 2008-09-18T15:55:24Z | [
"python",
"xml",
"streaming"
] |
What's the easiest non-memory intensive way to output XML from Python? | 93,710 | <p>Basically, something similar to System.Xml.XmlWriter - A streaming XML Writer that doesn't incur much of a memory overhead. So that rules out xml.dom and xml.dom.minidom. Suggestions?</p>
| 12 | 2008-09-18T15:42:19Z | 93,871 | <p>I've always had good results with <a href="http://codespeak.net/lxml/" rel="nofollow">lxml</a>. It's a pain to install, as it's mostly a wrapper around <a href="http://xmlsoft.org/" rel="nofollow">libxml2</a>, but <code>lxml.etree</code> tree objects have a <code>.write()</code> method that takes a file-like object to stream to.</p>
<pre><code>from lxml.etree import XML
tree = XML('<root><a><b/></a></root>')
tree.write(your_file_object)
</code></pre>
| -1 | 2008-09-18T15:57:23Z | [
"python",
"xml",
"streaming"
] |
What's the easiest non-memory intensive way to output XML from Python? | 93,710 | <p>Basically, something similar to System.Xml.XmlWriter - A streaming XML Writer that doesn't incur much of a memory overhead. So that rules out xml.dom and xml.dom.minidom. Suggestions?</p>
| 12 | 2008-09-18T15:42:19Z | 93,984 | <p>Some years ago I used <code>MarkupWriter</code> from <a href="http://4suite.org/index.xhtml" rel="nofollow">4suite</a></p>
<blockquote>
<pre><code>General-purpose utility class for generating XML (may eventually be
expanded to produce more output types)
Sample usage:
from Ft.Xml import MarkupWriter
writer = MarkupWriter(indent=u"yes")
writer.startDocument()
writer.startElement(u'xsa')
writer.startElement(u'vendor')
#Element with simple text (#PCDATA) content
writer.simpleElement(u'name', content=u'Centigrade systems')
#Note writer.text(content) still works
writer.simpleElement(u'email', content=u"[email protected]")
writer.endElement(u'vendor')
#Element with an attribute
writer.startElement(u'product', attributes={u'id': u"100\u00B0"})
#Note writer.attribute(name, value, namespace=None) still works
writer.simpleElement(u'name', content=u"100\u00B0 Server")
#XML fragment
writer.xmlFragment('<version>1.0</version><last-release>20030401</last-release>')
#Empty element
writer.simpleElement(u'changes')
writer.endElement(u'product')
writer.endElement(u'xsa')
writer.endDocument()
Note on the difference between 4Suite writers and printers
Writer - module that exposes a broad public API for building output
bit by bit
Printer - module that simply takes a DOM and creates output from it
as a whole, within one API invokation
</code></pre>
</blockquote>
<p>Recently i hear a lot about how <a href="http://codespeak.net/lxml/" rel="nofollow">lxml</a> is great, but I don't have first-hand experience, and I had some fun working with <a href="http://freshmeat.net/projects/gnosisxml/" rel="nofollow">gnosis</a>.</p>
| 0 | 2008-09-18T16:08:21Z | [
"python",
"xml",
"streaming"
] |
What's the easiest non-memory intensive way to output XML from Python? | 93,710 | <p>Basically, something similar to System.Xml.XmlWriter - A streaming XML Writer that doesn't incur much of a memory overhead. So that rules out xml.dom and xml.dom.minidom. Suggestions?</p>
| 12 | 2008-09-18T15:42:19Z | 94,114 | <p>I think you'll find XMLGenerator from xml.sax.saxutils is the closest thing to what you want.</p>
<pre>
import time
from xml.sax.saxutils import XMLGenerator
from xml.sax.xmlreader import AttributesNSImpl
LOG_LEVELS = ['DEBUG', 'WARNING', 'ERROR']
class xml_logger:
def __init__(self, output, encoding):
"""
Set up a logger object, which takes SAX events and outputs
an XML log file
"""
logger = XMLGenerator(output, encoding)
logger.startDocument()
attrs = AttributesNSImpl({}, {})
logger.startElementNS((None, u'log'), u'log', attrs)
self._logger = logger
self._output = output
self._encoding = encoding
return
def write_entry(self, level, msg):
"""
Write a log entry to the logger
level - the level of the entry
msg - the text of the entry. Must be a Unicode object
"""
#Note: in a real application, I would use ISO 8601 for the date
#asctime used here for simplicity
now = time.asctime(time.localtime())
attr_vals = {
(None, u'date'): now,
(None, u'level'): LOG_LEVELS[level],
}
attr_qnames = {
(None, u'date'): u'date',
(None, u'level'): u'level',
}
attrs = AttributesNSImpl(attr_vals, attr_qnames)
self._logger.startElementNS((None, u'entry'), u'entry', attrs)
self._logger.characters(msg)
self._logger.endElementNS((None, u'entry'), u'entry')
return
def close(self):
"""
Clean up the logger object
"""
self._logger.endElementNS((None, u'log'), u'log')
self._logger.endDocument()
return
if __name__ == "__main__":
#Test it out
import sys
xl = xml_logger(sys.stdout, 'utf-8')
xl.write_entry(2, u"Vanilla log entry")
xl.close()
</pre>
<p>You'll probably want to look at the rest of the article I got that from at <a href="http://www.xml.com/pub/a/2003/03/12/py-xml.html">http://www.xml.com/pub/a/2003/03/12/py-xml.html</a>.</p>
| 13 | 2008-09-18T16:22:28Z | [
"python",
"xml",
"streaming"
] |
What's the easiest non-memory intensive way to output XML from Python? | 93,710 | <p>Basically, something similar to System.Xml.XmlWriter - A streaming XML Writer that doesn't incur much of a memory overhead. So that rules out xml.dom and xml.dom.minidom. Suggestions?</p>
| 12 | 2008-09-18T15:42:19Z | 97,581 | <p>Second vote for ElementTree (cElementTree is a C implementation that is a little faster, like cPickle vs pickle). There's some short example code here that you can look at to give you an idea of how it works: <a href="http://effbot.org/zone/element-index.htm" rel="nofollow">http://effbot.org/zone/element-index.htm</a>
(this is Fredrik Lundh, who wrote the module in the first place. It's so good it got drafted into the standard library with 2.5 :-) )</p>
| -2 | 2008-09-18T22:17:07Z | [
"python",
"xml",
"streaming"
] |
How do I persist to disk a temporary file using Python? | 94,153 | <p>I am attempting to use the 'tempfile' module for manipulating and creating text files. Once the file is ready I want to save it to disk. I thought it would be as simple as using 'shutil.copy'. However, I get a 'permission denied' IOError:</p>
<pre><code>>>> import tempfile, shutil
>>> f = tempfile.TemporaryFile(mode ='w+t')
>>> f.write('foo')
>>> shutil.copy(f.name, 'bar.txt')
Traceback (most recent call last):
File "<pyshell#5>", line 1, in <module>
shutil.copy(f.name, 'bar.txt')
File "C:\Python25\lib\shutil.py", line 80, in copy
copyfile(src, dst)
File "C:\Python25\lib\shutil.py", line 46, in copyfile
fsrc = open(src, 'rb')
IOError: [Errno 13] Permission denied: 'c:\\docume~1\\me\\locals~1\\temp\\tmpvqq3go'
>>>
</code></pre>
<p>Is this not intended when using the 'tempfile' library? Is there a better way to do this? (Maybe I am overlooking something very trivial)</p>
| 13 | 2008-09-18T16:27:26Z | 94,206 | <p>You could always use <em>shutil.copyfileobj</em>, in your example:</p>
<pre><code>new_file = open('bar.txt', 'rw')
shutil.copyfileobj(f, new_file)
</code></pre>
| 4 | 2008-09-18T16:33:46Z | [
"python",
"temporary-files"
] |
How do I persist to disk a temporary file using Python? | 94,153 | <p>I am attempting to use the 'tempfile' module for manipulating and creating text files. Once the file is ready I want to save it to disk. I thought it would be as simple as using 'shutil.copy'. However, I get a 'permission denied' IOError:</p>
<pre><code>>>> import tempfile, shutil
>>> f = tempfile.TemporaryFile(mode ='w+t')
>>> f.write('foo')
>>> shutil.copy(f.name, 'bar.txt')
Traceback (most recent call last):
File "<pyshell#5>", line 1, in <module>
shutil.copy(f.name, 'bar.txt')
File "C:\Python25\lib\shutil.py", line 80, in copy
copyfile(src, dst)
File "C:\Python25\lib\shutil.py", line 46, in copyfile
fsrc = open(src, 'rb')
IOError: [Errno 13] Permission denied: 'c:\\docume~1\\me\\locals~1\\temp\\tmpvqq3go'
>>>
</code></pre>
<p>Is this not intended when using the 'tempfile' library? Is there a better way to do this? (Maybe I am overlooking something very trivial)</p>
| 13 | 2008-09-18T16:27:26Z | 94,339 | <p>The file you create with <code>TemporaryFile</code> or <code>NamedTemporaryFile</code> is automatically removed when it's closed, which is why you get an error. If you don't want this, you can use <code>mkstemp</code> instead (see the docs for <a href="http://docs.python.org/lib/module-tempfile.html">tempfile</a>).</p>
<pre><code>>>> import tempfile, shutil, os
>>> fd, path = tempfile.mkstemp()
>>> os.write(fd, 'foo')
>>> os.close(fd)
>>> shutil.copy(path, 'bar.txt')
>>> os.remove(path)
</code></pre>
| 16 | 2008-09-18T16:45:37Z | [
"python",
"temporary-files"
] |
How do I persist to disk a temporary file using Python? | 94,153 | <p>I am attempting to use the 'tempfile' module for manipulating and creating text files. Once the file is ready I want to save it to disk. I thought it would be as simple as using 'shutil.copy'. However, I get a 'permission denied' IOError:</p>
<pre><code>>>> import tempfile, shutil
>>> f = tempfile.TemporaryFile(mode ='w+t')
>>> f.write('foo')
>>> shutil.copy(f.name, 'bar.txt')
Traceback (most recent call last):
File "<pyshell#5>", line 1, in <module>
shutil.copy(f.name, 'bar.txt')
File "C:\Python25\lib\shutil.py", line 80, in copy
copyfile(src, dst)
File "C:\Python25\lib\shutil.py", line 46, in copyfile
fsrc = open(src, 'rb')
IOError: [Errno 13] Permission denied: 'c:\\docume~1\\me\\locals~1\\temp\\tmpvqq3go'
>>>
</code></pre>
<p>Is this not intended when using the 'tempfile' library? Is there a better way to do this? (Maybe I am overlooking something very trivial)</p>
| 13 | 2008-09-18T16:27:26Z | 109,591 | <p>Starting from python 2.6 you can also use <code>NamedTemporaryFile</code> with the <code>delete=</code> option set to False. This way the temporary file will be accessible, even after you close it.</p>
<p>Note that on Windows (NT and later) you cannot access the file a second time while it is still open. You have to close it before you can copy it. This is not true on Unix systems.</p>
| 11 | 2008-09-20T22:15:33Z | [
"python",
"temporary-files"
] |
How do I persist to disk a temporary file using Python? | 94,153 | <p>I am attempting to use the 'tempfile' module for manipulating and creating text files. Once the file is ready I want to save it to disk. I thought it would be as simple as using 'shutil.copy'. However, I get a 'permission denied' IOError:</p>
<pre><code>>>> import tempfile, shutil
>>> f = tempfile.TemporaryFile(mode ='w+t')
>>> f.write('foo')
>>> shutil.copy(f.name, 'bar.txt')
Traceback (most recent call last):
File "<pyshell#5>", line 1, in <module>
shutil.copy(f.name, 'bar.txt')
File "C:\Python25\lib\shutil.py", line 80, in copy
copyfile(src, dst)
File "C:\Python25\lib\shutil.py", line 46, in copyfile
fsrc = open(src, 'rb')
IOError: [Errno 13] Permission denied: 'c:\\docume~1\\me\\locals~1\\temp\\tmpvqq3go'
>>>
</code></pre>
<p>Is this not intended when using the 'tempfile' library? Is there a better way to do this? (Maybe I am overlooking something very trivial)</p>
| 13 | 2008-09-18T16:27:26Z | 9,155,528 | <p>hop is right, and dF. is incorrect on why the error occurs.</p>
<p>Since you haven't called <code>f.close()</code> yet, the file is <strong>not</strong> removed. </p>
<p>The <a href="http://docs.python.org/library/tempfile.html#tempfile.NamedTemporaryFile">doc</a> for <code>NamedTemporaryFile</code> says: </p>
<blockquote>
<p>Whether the name can be used to open the file a second time, while the named temporary file is still open, varies across platforms (it can be so used on Unix; it cannot on Windows NT or later). </p>
</blockquote>
<p>And for <code>TemporaryFile</code>:</p>
<blockquote>
<p>Under Unix, the directory entry for the file is removed immediately after the file is created. Other platforms do not support this; your code should not rely on a temporary file created using this function having or not having a visible name in the file system.</p>
</blockquote>
<p>Therefore, to persist a temporary file (on Windows), you can do the following:</p>
<pre><code>>>> import tempfile, shutil
>>> f = tempfile.NamedTemporaryFile(mode='w+t', delete=False)
>>> f.write('foo')
>>> file_name = f.name
>>> f.close()
>>> shutil.copy(file_name, 'bar.txt')
</code></pre>
<p>The solution Hans Sjunnesson provided is also off, because <code>copyfileobj</code> only copies from file-like object to file-like object, not file name:</p>
<blockquote>
<p>shutil.copyfileobj(fsrc, fdst[, length])</p>
<blockquote>
<p>Copy the contents of the file-like object fsrc to the file-like object fdst. The integer length, if given, is the buffer size. In particular, a negative length value means to copy the data without looping over the source data in chunks; by default the data is read in chunks to avoid uncontrolled memory consumption. Note that if the current file position of the fsrc object is not 0, only the contents from the current file position to the end of the file will be copied.</p>
</blockquote>
</blockquote>
| 28 | 2012-02-06T04:19:42Z | [
"python",
"temporary-files"
] |
Distributed python | 94,334 | <p>What is the best python framework to create distributed applications? For example to build a P2P app.</p>
| 6 | 2008-09-18T16:45:07Z | 94,385 | <p>You could download the source of BitTorrent for starters and see how they did it.</p>
<p><a href="http://download.bittorrent.com/dl/" rel="nofollow">http://download.bittorrent.com/dl/</a></p>
| 1 | 2008-09-18T16:50:48Z | [
"python",
"distributed"
] |
Distributed python | 94,334 | <p>What is the best python framework to create distributed applications? For example to build a P2P app.</p>
| 6 | 2008-09-18T16:45:07Z | 94,434 | <p>If it's something where you're going to need tons of threads and need better concurrent performance, check out <a href="http://www.stackless.com/" rel="nofollow">Stackless Python</a>. Otherwise you could just use the <a href="http://en.wikipedia.org/wiki/SOAP" rel="nofollow">SOAP</a> or <a href="http://www.xmlrpc.com/" rel="nofollow">XML-RPC</a> protocols. In response to Ben's post, if you don't want to look over the BitTorrent source, you could just look at the article on <a href="http://en.wikipedia.org/wiki/BitTorrent_(protocol)" rel="nofollow">the BitTorrent protocol</a>.</p>
| 1 | 2008-09-18T16:55:34Z | [
"python",
"distributed"
] |
Distributed python | 94,334 | <p>What is the best python framework to create distributed applications? For example to build a P2P app.</p>
| 6 | 2008-09-18T16:45:07Z | 94,510 | <p>You could checkout <a href="http://pyprocessing.berlios.de/" rel="nofollow">pyprocessing</a> which will be included in the standard library as of 2.6. It allows you to run tasks on multiple processes using an API similar to threading.</p>
| 2 | 2008-09-18T17:07:00Z | [
"python",
"distributed"
] |
Distributed python | 94,334 | <p>What is the best python framework to create distributed applications? For example to build a P2P app.</p>
| 6 | 2008-09-18T16:45:07Z | 94,597 | <p>I think you mean "Networked Apps"? Distributed means an app that can split its workload among multiple worker clients over the network. </p>
<p>You probably want.
<a href="http://twistedmatrix.com/trac/">Twisted</a></p>
| 9 | 2008-09-18T17:18:53Z | [
"python",
"distributed"
] |
Distributed python | 94,334 | <p>What is the best python framework to create distributed applications? For example to build a P2P app.</p>
| 6 | 2008-09-18T16:45:07Z | 111,300 | <p>You probably want <a href="http://twistedmatrix.com/trac/" rel="nofollow">Twisted</a>. There is a P2P framework for Twisted called "<a href="http://divmod.org/trac/wiki/DivmodVertex" rel="nofollow">Vertex</a>". While not actively maintained, it does allow you to tunnel through NATs and make connections directly between users in a very abstract way; if there were more interest in this sort of thing I'm sure it would be more actively maintained.</p>
| 3 | 2008-09-21T16:03:08Z | [
"python",
"distributed"
] |
How do I read selected files from a remote Zip archive over HTTP using Python? | 94,490 | <p>I need to read selected files, matching on the file name, from a remote zip archive using Python. I don't want to save the full zip to a temporary file (it's not that large, so I can handle everything in memory).</p>
<p>I've already written the code and it works, and I'm answering this myself so I can search for it later. But since evidence suggests that I'm one of the dumber participants on Stackoverflow, I'm sure there's room for improvement.</p>
| 9 | 2008-09-18T17:03:36Z | 94,491 | <p>Here's how I did it (grabbing all files ending in ".ranks"):</p>
<pre><code>import urllib2, cStringIO, zipfile
try:
remotezip = urllib2.urlopen(url)
zipinmemory = cStringIO.StringIO(remotezip.read())
zip = zipfile.ZipFile(zipinmemory)
for fn in zip.namelist():
if fn.endswith(".ranks"):
ranks_data = zip.read(fn)
for line in ranks_data.split("\n"):
# do something with each line
except urllib2.HTTPError:
# handle exception
</code></pre>
| 8 | 2008-09-18T17:03:42Z | [
"python",
"http",
"zip"
] |
How do I read selected files from a remote Zip archive over HTTP using Python? | 94,490 | <p>I need to read selected files, matching on the file name, from a remote zip archive using Python. I don't want to save the full zip to a temporary file (it's not that large, so I can handle everything in memory).</p>
<p>I've already written the code and it works, and I'm answering this myself so I can search for it later. But since evidence suggests that I'm one of the dumber participants on Stackoverflow, I'm sure there's room for improvement.</p>
| 9 | 2008-09-18T17:03:36Z | 94,516 | <p>Bear in mind that merely decompressing a ZIP file may result in <a href="http://en.wikipedia.org/wiki/Decompression_bomb" rel="nofollow">a security vulnerability</a>.</p>
| 1 | 2008-09-18T17:07:38Z | [
"python",
"http",
"zip"
] |
How do I read selected files from a remote Zip archive over HTTP using Python? | 94,490 | <p>I need to read selected files, matching on the file name, from a remote zip archive using Python. I don't want to save the full zip to a temporary file (it's not that large, so I can handle everything in memory).</p>
<p>I've already written the code and it works, and I'm answering this myself so I can search for it later. But since evidence suggests that I'm one of the dumber participants on Stackoverflow, I'm sure there's room for improvement.</p>
| 9 | 2008-09-18T17:03:36Z | 952,834 | <p>Thanks Marcel for your question and answer (I had the same problem in a different context and encountered the same difficulty with file-like objects not really being file-like)! Just as an update: For Python 3.0, your code needs to be modified slightly:</p>
<pre><code>import urllib.request, io, zipfile
try:
remotezip = urllib.request.urlopen(url)
zipinmemory = io.BytesIO(remotezip.read())
zip = zipfile.ZipFile(zipinmemory)
for fn in zip.namelist():
if fn.endswith(".ranks"):
ranks_data = zip.read(fn)
for line in ranks_data.split("\n"):
# do something with each line
except urllib.request.HTTPError:
# handle exception
</code></pre>
| 2 | 2009-06-04T20:13:44Z | [
"python",
"http",
"zip"
] |
How do I read selected files from a remote Zip archive over HTTP using Python? | 94,490 | <p>I need to read selected files, matching on the file name, from a remote zip archive using Python. I don't want to save the full zip to a temporary file (it's not that large, so I can handle everything in memory).</p>
<p>I've already written the code and it works, and I'm answering this myself so I can search for it later. But since evidence suggests that I'm one of the dumber participants on Stackoverflow, I'm sure there's room for improvement.</p>
| 9 | 2008-09-18T17:03:36Z | 14,461,148 | <p>This will do the job without downloading the entire zip file!</p>
<p><a href="http://pypi.python.org/pypi/pyremotezip" rel="nofollow">http://pypi.python.org/pypi/pyremotezip</a></p>
| 2 | 2013-01-22T14:43:27Z | [
"python",
"http",
"zip"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 94,953 | <p>See this <a href="http://avinashv.net/2008/05/pythons-range-and-xrange/" rel="nofollow">post</a> to find difference between range and xrange:</p>
<p>To quote:</p>
<blockquote>
<p><code>range</code> returns exactly what you think: a list of consecutive
integers, of a defined length beginning with 0. <code>xrange</code>, however,
returns an <em>"xrange object"</em>, which acts a great deal like an iterator</p>
</blockquote>
| 0 | 2008-09-18T17:54:40Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 94,957 | <p>xrange returns an iterator and only keeps one number in memory at a time. range keeps the entire list of numbers in memory.</p>
| 25 | 2008-09-18T17:55:00Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 94,962 | <p>range creates a list, so if you do <code>range(1, 10000000)</code> it creates a list in memory with <code>9999999</code> elements.</p>
<p><code>xrange</code> is a sequence object that evaluates lazily. </p>
| 460 | 2008-09-18T17:55:13Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 94,965 | <p>range generates the entire list and returns it. xrange does not -- it generates the numbers in the list on demand.</p>
| 2 | 2008-09-18T17:55:27Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 94,966 | <p>xrange uses an iterator (generates values on the fly), range returns a list.</p>
| 2 | 2008-09-18T17:55:30Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 94,971 | <p>Do spend some time with the <a href="http://docs.python.org/lib/typesseq-xrange.html">Library Reference</a>. The more familiar you are with it, the faster you can find answers to questions like this. Especially important are the first few chapters about builtin objects and types.</p>
<blockquote>
<p>The advantage of the xrange type is that an xrange object will always
take the same amount of memory, no matter the size of the range it represents.
There are no consistent performance advantages.</p>
</blockquote>
<p>Another way to find quick information about a Python construct is the docstring and the help-function:</p>
<pre><code>print xrange.__doc__ # def doc(x): print x.__doc__ is super useful
help(xrange)
</code></pre>
| 18 | 2008-09-18T17:55:59Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 95,010 | <p>It is for optimization reasons.</p>
<p>range() will create a list of values from start to end (0 .. 20 in your example). This will become an expensive operation on very large ranges.</p>
<p>xrange() on the other hand is much more optimised. it will only compute the next value when needed (via an xrange sequence object) and does not create a list of all values like range() does.</p>
| 8 | 2008-09-18T17:59:46Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 95,100 | <blockquote>
<p>range creates a list, so if you do <code>range(1, 10000000)</code> it creates a list in memory with <code>10000000</code> elements.</p>
<p><code>xrange</code> <s>is a generator, so it</s> is a sequence object <s>is a</s> that evaluates lazily. </p>
</blockquote>
<p>This is true, but in Python 3, range will be implemented by the Python 2 xrange(). If you need to actually generate the list, you will need to do:</p>
<pre><code>list(range(1,100))
</code></pre>
| 148 | 2008-09-18T18:08:19Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 95,168 | <p><code>xrange</code> only stores the range params and generates the numbers on demand. However the C implementation of Python currently restricts its args to C longs:</p>
<pre><code>xrange(2**32-1, 2**32+1) # When long is 32 bits, OverflowError: Python int too large to convert to C long
range(2**32-1, 2**32+1) # OK --> [4294967295L, 4294967296L]
</code></pre>
<p>Note that in Python 3.0 there is only <code>range</code> and it behaves like the 2.x <code>xrange</code> but without the limitations on minimum and maximum end points.</p>
| 51 | 2008-09-18T18:13:44Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 95,549 | <blockquote>
<p>range creates a list, so if you do range(1, 10000000) it creates a list in memory with 10000000 elements.
xrange is a generator, so it evaluates lazily.</p>
</blockquote>
<p>This brings you two advantages:</p>
<ol>
<li>You can iterate longer lists without getting a <code>MemoryError</code>.</li>
<li>As it resolves each number lazily, if you stop iteration early, you won't waste time creating the whole list.</li>
</ol>
| 10 | 2008-09-18T18:44:38Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 97,530 | <p>Remember, use the timeit module to test which of small snipps of code is faster!</p>
<pre><code>$ python -m timeit 'for i in range(1000000):' ' pass'
10 loops, best of 3: 90.5 msec per loop
$ python -m timeit 'for i in xrange(1000000):' ' pass'
10 loops, best of 3: 51.1 msec per loop
</code></pre>
<p>Personally, I always use range(), unless I were dealing with <em>really</em> huge lists -- as you can see, time-wise, for a list of a million entries, the extra overhead is only 0.04 seconds. And as Corey points out, in Python 3.0 xrange will go away and range will give you nice iterator behaviour anyway.</p>
| 77 | 2008-09-18T22:11:15Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 5,351,725 | <p>When testing range against xrange in a loop (I know I should use <a href="http://docs.python.org/library/timeit.html" rel="nofollow">timeit</a>, but this was swiftly hacked up from memory using a simple list comprehension example) I found the following:</p>
<pre><code>import time
for x in range(1, 10):
t = time.time()
[v*10 for v in range(1, 10000)]
print "range: %.4f" % ((time.time()-t)*100)
t = time.time()
[v*10 for v in xrange(1, 10000)]
print "xrange: %.4f" % ((time.time()-t)*100)
</code></pre>
<p>which gives:</p>
<pre><code>$python range_tests.py
range: 0.4273
xrange: 0.3733
range: 0.3881
xrange: 0.3507
range: 0.3712
xrange: 0.3565
range: 0.4031
xrange: 0.3558
range: 0.3714
xrange: 0.3520
range: 0.3834
xrange: 0.3546
range: 0.3717
xrange: 0.3511
range: 0.3745
xrange: 0.3523
range: 0.3858
xrange: 0.3997 <- garbage collection?
</code></pre>
<p>Or, using xrange in the for loop:</p>
<pre><code>range: 0.4172
xrange: 0.3701
range: 0.3840
xrange: 0.3547
range: 0.3830
xrange: 0.3862 <- garbage collection?
range: 0.4019
xrange: 0.3532
range: 0.3738
xrange: 0.3726
range: 0.3762
xrange: 0.3533
range: 0.3710
xrange: 0.3509
range: 0.3738
xrange: 0.3512
range: 0.3703
xrange: 0.3509
</code></pre>
<p>Is my snippet testing properly? Any comments on the slower instance of xrange? Or a better example :-)</p>
| 2 | 2011-03-18T12:04:59Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 21,137,807 | <p>On a requirement for scanning/printing of 0-N items , range and xrange works as follows.</p>
<p>range() - creates a new list in the memory and takes the whole 0 to N items(totally N+1) and prints them.
xrange() - creates a iterator instance that scans through the items and keeps only the current encountered item into the memory , hence utilising same amount of memory all the time.</p>
<p>In case the required element is somewhat at the beginning of the list only then it saves a good amount of time and memory.</p>
| 1 | 2014-01-15T12:45:29Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 22,905,006 | <p>I am shocked nobody read <a href="https://docs.python.org/2/library/functions.html#xrange" rel="nofollow">doc</a></p>
<p>This function is very similar to range(), but returns an xrange object instead of a list. This is an opaque sequence type which yields the same values as the corresponding list, without actually storing them all simultaneously. The advantage of xrange() over range() is minimal (since xrange() still has to create the values when asked for them) except when a very large range is used on a memory-starved machine or when all of the rangeâs elements are never used (such as when the loop is usually terminated with break).</p>
| 4 | 2014-04-07T06:25:25Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 27,144,195 | <p>What?<br>
<code>range</code> returns a static list at runtime.<br>
<code>xrange</code> returns an <code>object</code> (which acts like a generator, although it's certainly not one) from which values are generated as and when required.</p>
<p>When to use which? </p>
<ul>
<li>Use <code>xrange</code> if you want to generate a list for a gigantic range, say 1 billion, especially when you have a "memory sensitive system" like a cell phone.</li>
<li>Use <code>range</code> if you want to iterate over the list several times.</li>
</ul>
<p>PS: Python 3.x's <code>range</code> function == Python 2.x's <code>xrange</code> function.</p>
| 2 | 2014-11-26T08:18:28Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 27,752,378 | <p><strong>Range</strong> returns a <strong>list</strong> while <strong>xrange</strong> returns an <strong>xrange</strong> object which takes the same memory irrespective of the range size,as in this case,only one element is generated and available per iteration whereas in case of using range, all the elements are generated at once and are available in the memory.</p>
| 0 | 2015-01-03T06:31:21Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 30,088,340 | <p>Some of the other answers mention that Python 3 eliminated 2.x's <code>range</code> and renamed 2.x's <code>xrange</code> to <code>range</code>. However, unless you're using 3.0 or 3.1 (which nobody should be), it's actually a somewhat different type.</p>
<p>As <a href="https://docs.python.org/3.1/library/stdtypes.html#range-type" rel="nofollow">the 3.1 docs</a> say:</p>
<blockquote>
<p>Range objects have very little behavior: they only support indexing, iteration, and the <code>len</code> function.</p>
</blockquote>
<p>However, in 3.2+, <code>range</code> is a full sequenceâit supports extended slices, and all of the methods of <a href="https://docs.python.org/3/library/collections.abc.html#collections-abstract-base-classes" rel="nofollow"><code>collections.abc.Sequence</code></a> with the same semantics as a <code>list</code>.<sup>*</sup></p>
<p>And, at least in CPython and PyPy (the only two 3.2+ implementations that currently exist), it also has constant-time implementations of the <code>index</code> and <code>count</code> methods and the <code>in</code> operator (as long as you only pass it integers). This means writing <code>123456 in r</code> is reasonable in 3.2+, while in 2.7 or 3.1 it would be a horrible idea.</p>
<hr>
<p><sub>* The fact that <code>issubclass(xrange, collections.Sequence)</code> returns <code>True</code> in 2.6-2.7 and 3.0-3.1 is <a href="http://bugs.python.org/issue9213" rel="nofollow">a bug</a> that was fixed in 3.2 and not backported.</sub></p>
| 3 | 2015-05-06T21:57:10Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 30,545,536 | <p>The difference decreases for smaller arguments to <code>range(..)</code> / <code>xrange(..)</code>:</p>
<pre><code>$ python -m timeit "for i in xrange(10111):" " for k in range(100):" " pass"
10 loops, best of 3: 59.4 msec per loop
$ python -m timeit "for i in xrange(10111):" " for k in xrange(100):" " pass"
10 loops, best of 3: 46.9 msec per loop
</code></pre>
<p>In this case <code>xrange(100)</code> is only about 20% more efficient.</p>
| 1 | 2015-05-30T11:23:20Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 30,997,385 | <p><strong>range():</strong> range(1, 10) returns a list from 1 to 10 numbers & hold whole list in memory.</p>
<p><strong>xrange():</strong> Like range(), but instead of returning a list, returns an object that generates the numbers in the range on demand. For looping, this is lightly faster than range() and more memory efficient.
xrange() object like an iterator and generates the numbers on demand.(Lazy Evaluation)</p>
<pre><code>In [1]: range(1,10)
Out[1]: [1, 2, 3, 4, 5, 6, 7, 8, 9]
In [2]: xrange(10)
Out[2]: xrange(10)
In [3]: print xrange.__doc__
xrange([start,] stop[, step]) -> xrange object
</code></pre>
| 6 | 2015-06-23T08:16:59Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 31,761,387 | <p>Read the following post for the comparison between range and xrange with graphical analysis.</p>
<p><a href="http://justindailey.blogspot.in/2011/09/python-range-vs-xrange.html" rel="nofollow">Python range Vs xrange</a></p>
| 2 | 2015-08-01T11:37:56Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 34,877,258 | <p>xrange() and range() in python works similarly as for the user , but the difference comes when we are talking about how the memory is allocated in using both the function.</p>
<p>When we are using range() we allocate memory for all the variables it is generating, so it is not recommended to use with larger no. of variables to be generated.</p>
<p>xrange() on the other hand generate only a particular value at a time and can only be used with the for loop to print all the values required.</p>
| 4 | 2016-01-19T12:48:45Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 35,680,931 | <p>In python 2.x</p>
<p><strong>range(x)</strong> returns a list, that is created in memory with x elements.</p>
<pre><code>>>> a = range(5)
>>> a
[0, 1, 2, 3, 4]
</code></pre>
<p><strong>xrange(x)</strong> returns an xrange object which is a generator obj which generates the numbers on demand. they are computed during for-loop(Lazy Evaluation).</p>
<p>For looping, this is slightly faster than range() and more memory efficient.</p>
<pre><code>>>> b = xrange(5)
>>> b
xrange(5)
</code></pre>
| 3 | 2016-02-28T09:42:31Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
What is the difference between range and xrange functions in Python 2.X? | 94,935 | <p>Apparently xrange is faster but I have no idea why it's faster (and no proof besides the anecdotal so far that it is faster) or what besides that is different about</p>
<pre><code>for i in range(0, 20):
for i in xrange(0, 20):
</code></pre>
| 378 | 2008-09-18T17:52:51Z | 38,318,039 | <p><code>range(x,y)</code> returns a list of each number in between x and y if you use a <code>for</code> loop, then <code>range</code> is slower. In fact, <code>range</code> has a bigger Index range. <code>range(x.y)</code> will print out a list of all the numbers in between x and y</p>
<p><code>xrange(x,y)</code> returns <code>xrange(x,y)</code> but if you used a <code>for</code> loop, then <code>xrange</code> is faster. <code>xrange</code> has a smaller Index range. <code>xrange</code> will not only print out <code>xrange(x,y)</code> but it will still keep all the numbers that are in it.</p>
<pre><code>[In] range(1,10)
[Out] [1, 2, 3, 4, 5, 6, 7, 8, 9]
[In] xrange(1,10)
[Out] xrange(1,10)
</code></pre>
<p>If you use a <code>for</code> loop, then it would work</p>
<pre><code>[In] for i in range(1,10):
print i
[Out] 1
2
3
4
5
6
7
8
9
[In] for i in xrange(1,10):
print i
[Out] 1
2
3
4
5
6
7
8
9
</code></pre>
| 4 | 2016-07-12T00:05:27Z | [
"python",
"loops",
"range",
"python-2.x",
"xrange"
] |
Python implementation of Parsec? | 94,952 | <p>I recently wrote a parser in Python using Ply (it's a python reimplementation of yacc). When I was almost done with the parser I discovered that the grammar I need to parse requires me to do some look up during parsing to inform the lexer. Without doing a look up to inform the lexer I cannot correctly parse the strings in the language.</p>
<p>Given than I can control the state of the lexer from the grammar rules I think I'll be solving my use case using a look up table in the parser module, but it may become too difficult to maintain/test. So I want to know about some of the other options.</p>
<p>In Haskell I would use Parsec, a library of parsing functions (known as combinators). Is there a Python implementation of Parsec? Or perhaps some other production quality library full of parsing functionality so I can build a context sensitive parser in Python?</p>
<p>EDIT: All my attempts at context free parsing have failed. For this reason, I don't expect ANTLR to be useful here.</p>
| 10 | 2008-09-18T17:54:39Z | 95,014 | <p>An option you may consider, if an LL parser is ok to you, is to give <a href="http://www.antlr.org/wiki/display/ANTLR3/Antlr3PythonTarget" rel="nofollow">ANTLR</a> a try, it can generate python too (actually it is LL(*) as they name it, * stands for the quantity of lookahead it can cope with).</p>
| 3 | 2008-09-18T18:00:05Z | [
"python",
"parsing",
"parsec",
"combinators"
] |
Python implementation of Parsec? | 94,952 | <p>I recently wrote a parser in Python using Ply (it's a python reimplementation of yacc). When I was almost done with the parser I discovered that the grammar I need to parse requires me to do some look up during parsing to inform the lexer. Without doing a look up to inform the lexer I cannot correctly parse the strings in the language.</p>
<p>Given than I can control the state of the lexer from the grammar rules I think I'll be solving my use case using a look up table in the parser module, but it may become too difficult to maintain/test. So I want to know about some of the other options.</p>
<p>In Haskell I would use Parsec, a library of parsing functions (known as combinators). Is there a Python implementation of Parsec? Or perhaps some other production quality library full of parsing functionality so I can build a context sensitive parser in Python?</p>
<p>EDIT: All my attempts at context free parsing have failed. For this reason, I don't expect ANTLR to be useful here.</p>
| 10 | 2008-09-18T17:54:39Z | 95,035 | <p>There's ANTLR, which is LL(*), there's PyParsing, which is more object friendly and is sort of like a DSL, and then there's <a href="http://www.canonware.com/Parsing/" rel="nofollow">Parsing</a> which is like OCaml's Menhir.</p>
| 1 | 2008-09-18T18:02:07Z | [
"python",
"parsing",
"parsec",
"combinators"
] |
Python implementation of Parsec? | 94,952 | <p>I recently wrote a parser in Python using Ply (it's a python reimplementation of yacc). When I was almost done with the parser I discovered that the grammar I need to parse requires me to do some look up during parsing to inform the lexer. Without doing a look up to inform the lexer I cannot correctly parse the strings in the language.</p>
<p>Given than I can control the state of the lexer from the grammar rules I think I'll be solving my use case using a look up table in the parser module, but it may become too difficult to maintain/test. So I want to know about some of the other options.</p>
<p>In Haskell I would use Parsec, a library of parsing functions (known as combinators). Is there a Python implementation of Parsec? Or perhaps some other production quality library full of parsing functionality so I can build a context sensitive parser in Python?</p>
<p>EDIT: All my attempts at context free parsing have failed. For this reason, I don't expect ANTLR to be useful here.</p>
| 10 | 2008-09-18T17:54:39Z | 95,102 | <p><a href="http://www.antlr.org/" rel="nofollow">ANTLR</a> is great and has the added benefit of working across multiple languages.</p>
| 0 | 2008-09-18T18:08:28Z | [
"python",
"parsing",
"parsec",
"combinators"
] |
Python implementation of Parsec? | 94,952 | <p>I recently wrote a parser in Python using Ply (it's a python reimplementation of yacc). When I was almost done with the parser I discovered that the grammar I need to parse requires me to do some look up during parsing to inform the lexer. Without doing a look up to inform the lexer I cannot correctly parse the strings in the language.</p>
<p>Given than I can control the state of the lexer from the grammar rules I think I'll be solving my use case using a look up table in the parser module, but it may become too difficult to maintain/test. So I want to know about some of the other options.</p>
<p>In Haskell I would use Parsec, a library of parsing functions (known as combinators). Is there a Python implementation of Parsec? Or perhaps some other production quality library full of parsing functionality so I can build a context sensitive parser in Python?</p>
<p>EDIT: All my attempts at context free parsing have failed. For this reason, I don't expect ANTLR to be useful here.</p>
| 10 | 2008-09-18T17:54:39Z | 95,417 | <p>PySec is another monadic parser, I don't know much about it, but it's worth looking at <a href="http://www.valuedlessons.com/2008/02/pysec-monadic-combinatoric-parsing-in.html" rel="nofollow">here</a></p>
| 4 | 2008-09-18T18:34:52Z | [
"python",
"parsing",
"parsec",
"combinators"
] |
Python implementation of Parsec? | 94,952 | <p>I recently wrote a parser in Python using Ply (it's a python reimplementation of yacc). When I was almost done with the parser I discovered that the grammar I need to parse requires me to do some look up during parsing to inform the lexer. Without doing a look up to inform the lexer I cannot correctly parse the strings in the language.</p>
<p>Given than I can control the state of the lexer from the grammar rules I think I'll be solving my use case using a look up table in the parser module, but it may become too difficult to maintain/test. So I want to know about some of the other options.</p>
<p>In Haskell I would use Parsec, a library of parsing functions (known as combinators). Is there a Python implementation of Parsec? Or perhaps some other production quality library full of parsing functionality so I can build a context sensitive parser in Python?</p>
<p>EDIT: All my attempts at context free parsing have failed. For this reason, I don't expect ANTLR to be useful here.</p>
| 10 | 2008-09-18T17:54:39Z | 95,707 | <p>I believe that <a href="http://pyparsing.wikispaces.com/">pyparsing</a> is based on the same principles as parsec.</p>
| 7 | 2008-09-18T18:58:12Z | [
"python",
"parsing",
"parsec",
"combinators"
] |
Python implementation of Parsec? | 94,952 | <p>I recently wrote a parser in Python using Ply (it's a python reimplementation of yacc). When I was almost done with the parser I discovered that the grammar I need to parse requires me to do some look up during parsing to inform the lexer. Without doing a look up to inform the lexer I cannot correctly parse the strings in the language.</p>
<p>Given than I can control the state of the lexer from the grammar rules I think I'll be solving my use case using a look up table in the parser module, but it may become too difficult to maintain/test. So I want to know about some of the other options.</p>
<p>In Haskell I would use Parsec, a library of parsing functions (known as combinators). Is there a Python implementation of Parsec? Or perhaps some other production quality library full of parsing functionality so I can build a context sensitive parser in Python?</p>
<p>EDIT: All my attempts at context free parsing have failed. For this reason, I don't expect ANTLR to be useful here.</p>
| 10 | 2008-09-18T17:54:39Z | 104,547 | <p>Nothing prevents you for diverting your parser from the "context free" path using PLY. You can pass information to the lexer during parsing, and in this way achieve full flexibility. I'm pretty sure that you can parse anything you want with PLY this way.</p>
<p>For a hands-on example, <a href="http://code.google.com/p/pycparser/" rel="nofollow">consider</a> - it is a parser for ANSI C written in Python with PLY. It solves the classic C typedef - identifier problem (that makes C's grammar non context-sensitive) by populating a symbol table in the parser that is being used in the lexer to resolve symbol names as either types or not.</p>
| 1 | 2008-09-19T18:58:07Z | [
"python",
"parsing",
"parsec",
"combinators"
] |
Does an application-wide exception handler make sense? | 95,642 | <p>Long story short, I have a substantial Python application that, among other things, does outcalls to "losetup", "mount", etc. on Linux. Essentially consuming system resources that must be released when complete.</p>
<p>If my application crashes, I want to ensure these system resources are properly released.</p>
<p>Does it make sense to do something like the following?</p>
<pre><code>def main():
# TODO: main application entry point
pass
def cleanup():
# TODO: release system resources here
pass
if __name__ == "__main__":
try:
main()
except:
cleanup()
raise
</code></pre>
<p>Is this something that is typically done? Is there a better way? Perhaps the destructor in a singleton class?</p>
| 10 | 2008-09-18T18:52:30Z | 95,659 | <p>Application wide handler is fine. They are great for logging. Just make sure that the application wide one is durable and is unlikely to crash itself.</p>
| 2 | 2008-09-18T18:54:18Z | [
"python",
"exception-handling"
] |
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