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""" | |
Module defining global singleton classes. | |
This module raises a RuntimeError if an attempt to reload it is made. In that | |
way the identities of the classes defined here are fixed and will remain so | |
even if numpy itself is reloaded. In particular, a function like the following | |
will still work correctly after numpy is reloaded:: | |
def foo(arg=np._NoValue): | |
if arg is np._NoValue: | |
... | |
That was not the case when the singleton classes were defined in the numpy | |
``__init__.py`` file. See gh-7844 for a discussion of the reload problem that | |
motivated this module. | |
""" | |
__ALL__ = [ | |
'ModuleDeprecationWarning', 'VisibleDeprecationWarning', '_NoValue' | |
] | |
# Disallow reloading this module so as to preserve the identities of the | |
# classes defined here. | |
if '_is_loaded' in globals(): | |
raise RuntimeError('Reloading numpy._globals is not allowed') | |
_is_loaded = True | |
class ModuleDeprecationWarning(DeprecationWarning): | |
"""Module deprecation warning. | |
The nose tester turns ordinary Deprecation warnings into test failures. | |
That makes it hard to deprecate whole modules, because they get | |
imported by default. So this is a special Deprecation warning that the | |
nose tester will let pass without making tests fail. | |
""" | |
ModuleDeprecationWarning.__module__ = 'numpy' | |
class VisibleDeprecationWarning(UserWarning): | |
"""Visible deprecation warning. | |
By default, python will not show deprecation warnings, so this class | |
can be used when a very visible warning is helpful, for example because | |
the usage is most likely a user bug. | |
""" | |
VisibleDeprecationWarning.__module__ = 'numpy' | |
class _NoValueType: | |
"""Special keyword value. | |
The instance of this class may be used as the default value assigned to a | |
keyword if no other obvious default (e.g., `None`) is suitable, | |
Common reasons for using this keyword are: | |
- A new keyword is added to a function, and that function forwards its | |
inputs to another function or method which can be defined outside of | |
NumPy. For example, ``np.std(x)`` calls ``x.std``, so when a ``keepdims`` | |
keyword was added that could only be forwarded if the user explicitly | |
specified ``keepdims``; downstream array libraries may not have added | |
the same keyword, so adding ``x.std(..., keepdims=keepdims)`` | |
unconditionally could have broken previously working code. | |
- A keyword is being deprecated, and a deprecation warning must only be | |
emitted when the keyword is used. | |
""" | |
__instance = None | |
def __new__(cls): | |
# ensure that only one instance exists | |
if not cls.__instance: | |
cls.__instance = super().__new__(cls) | |
return cls.__instance | |
# needed for python 2 to preserve identity through a pickle | |
def __reduce__(self): | |
return (self.__class__, ()) | |
def __repr__(self): | |
return "<no value>" | |
_NoValue = _NoValueType() | |