96 lines
3.0 KiB
Python
96 lines
3.0 KiB
Python
|
"""
|
||
|
|
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.
|
||
|
|
|
||
|
|
"""
|
||
|
|
import enum
|
||
|
|
|
||
|
|
from ._utils import set_module as _set_module
|
||
|
|
|
||
|
|
__all__ = ['_NoValue', '_CopyMode']
|
||
|
|
|
||
|
|
|
||
|
|
# 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 _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
|
||
|
|
|
||
|
|
def __repr__(self):
|
||
|
|
return "<no value>"
|
||
|
|
|
||
|
|
|
||
|
|
_NoValue = _NoValueType()
|
||
|
|
|
||
|
|
|
||
|
|
@_set_module("numpy")
|
||
|
|
class _CopyMode(enum.Enum):
|
||
|
|
"""
|
||
|
|
An enumeration for the copy modes supported
|
||
|
|
by numpy.copy() and numpy.array(). The following three modes are supported,
|
||
|
|
|
||
|
|
- ALWAYS: This means that a deep copy of the input
|
||
|
|
array will always be taken.
|
||
|
|
- IF_NEEDED: This means that a deep copy of the input
|
||
|
|
array will be taken only if necessary.
|
||
|
|
- NEVER: This means that the deep copy will never be taken.
|
||
|
|
If a copy cannot be avoided then a `ValueError` will be
|
||
|
|
raised.
|
||
|
|
|
||
|
|
Note that the buffer-protocol could in theory do copies. NumPy currently
|
||
|
|
assumes an object exporting the buffer protocol will never do this.
|
||
|
|
"""
|
||
|
|
|
||
|
|
ALWAYS = True
|
||
|
|
IF_NEEDED = False
|
||
|
|
NEVER = 2
|
||
|
|
|
||
|
|
def __bool__(self):
|
||
|
|
# For backwards compatibility
|
||
|
|
if self == _CopyMode.ALWAYS:
|
||
|
|
return True
|
||
|
|
|
||
|
|
if self == _CopyMode.IF_NEEDED:
|
||
|
|
return False
|
||
|
|
|
||
|
|
raise ValueError(f"{self} is neither True nor False.")
|