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Code Issues Projects Releases Packages Wiki Activity Actions 11

Close issue #16267: better docs for @abstractmethod composition

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Nick Coghlan 2012-12-08 22:56:02 +10:00
parent 8e18fc8c0b
commit cea27be888
2 changed files with 47 additions and 15 deletions
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59
Doc/library/abc.rst
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@ -208,16 +208,20 @@ The :mod:`abc` module also provides the following decorators:
A subclass of the built-in :func:`classmethod`, indicating an abstract
classmethod. Otherwise it is similar to :func:`abstractmethod`.
Usage::
This special case is deprecated, as the :func:`classmethod` decorator
is now correctly identified as abstract when applied to an abstract
method::
class C(metaclass=ABCMeta):
@abstractclassmethod
@classmethod
@abstractmethod
def my_abstract_classmethod(cls, ...):
...
.. versionadded:: 3.2
.. deprecated:: 3.3
Use :class:`classmethod` with :func:`abstractmethod` instead.
It is now possible to use :class:`classmethod` with
:func:`abstractmethod`, making this decorator redundant.
.. decorator:: abstractstaticmethod(function)
@ -225,21 +229,26 @@ The :mod:`abc` module also provides the following decorators:
A subclass of the built-in :func:`staticmethod`, indicating an abstract
staticmethod. Otherwise it is similar to :func:`abstractmethod`.
Usage::
This special case is deprecated, as the :func:`staticmethod` decorator
is now correctly identified as abstract when applied to an abstract
method::
class C(metaclass=ABCMeta):
@abstractstaticmethod
@staticmethod
@abstractmethod
def my_abstract_staticmethod(...):
...
.. versionadded:: 3.2
.. deprecated:: 3.3
Use :class:`staticmethod` with :func:`abstractmethod` instead.
It is now possible to use :class:`staticmethod` with
:func:`abstractmethod`, making this decorator redundant.
.. decorator:: abstractproperty(fget=None, fset=None, fdel=None, doc=None)
A subclass of the built-in :func:`property`, indicating an abstract property.
A subclass of the built-in :func:`property`, indicating an abstract
property.
Using this function requires that the class's metaclass is :class:`ABCMeta`
or is derived from it. A class that has a metaclass derived from
@ -247,23 +256,43 @@ The :mod:`abc` module also provides the following decorators:
and properties are overridden. The abstract properties can be called using
any of the normal 'super' call mechanisms.
Usage::
This special case is deprecated, as the :func:`property` decorator
is now correctly identified as abstract when applied to an abstract
method::
class C(metaclass=ABCMeta):
@abstractproperty
@property
@abstractmethod
def my_abstract_property(self):
...
This defines a read-only property; you can also define a read-write abstract
property using the 'long' form of property declaration::
The above example defines a read-only property; you can also define a
read-write abstract property by appropriately marking one or more of the
underlying methods as abstract::
class C(metaclass=ABCMeta):
def getx(self): ...
def setx(self, value): ...
x = abstractproperty(getx, setx)
@property
def x(self):
...
@x.setter
@abstractmethod
def x(self, val):
...
If only some components are abstract, only those components need to be
updated to create a concrete property in a subclass::
class D(C):
@C.x.setter
def x(self, val):
...
.. deprecated:: 3.3
Use :class:`property` with :func:`abstractmethod` instead
It is now possible to use :class:`property`, :meth:`property.getter`,
:meth:`property.setter` and :meth:`property.deleter` with
:func:`abstractmethod`, making this decorator redundant.
.. rubric:: Footnotes

3
Misc/NEWS
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@ -322,6 +322,9 @@ Tools/Demos
Documentation
-------------
- Issue #16267: Better document the 3.3+ approach to combining
@abstractmethod with @staticmethod, @classmethod and @property
- Issue #15209: Clarify exception chaining description in exceptions module
documentation