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benjaminpbenjaminp
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improve abstract property support (closes #11610)
Thanks to Darren Dale for patch.
1 parent a8ff01c commit bfebb7b

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Lines changed: 396 additions & 36 deletions

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‎Doc/library/abc.rst‎

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@@ -127,32 +127,71 @@ This module provides the following class:
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available as a method of ``Foo``, so it is provided separately.
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It also provides the following decorators:
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The :mod:`abc` module also provides the following decorators:
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.. decorator:: abstractmethod(function)
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A decorator indicating abstract methods.
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Using this decorator requires that the class's metaclass is :class:`ABCMeta` or
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is derived from it.
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A class that has a metaclass derived from :class:`ABCMeta`
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cannot be instantiated unless all of its abstract methods and
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properties are overridden.
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The abstract methods can be called using any of the normal 'super' call
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mechanisms.
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Using this decorator requires that the class's metaclass is :class:`ABCMeta`
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or is derived from it. A class that has a metaclass derived from
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:class:`ABCMeta` cannot be instantiated unless all of its abstract methods
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and properties are overridden. The abstract methods can be called using any
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of the normal 'super' call mechanisms. :func:`abstractmethod` may be used
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to declare abstract methods for properties and descriptors.
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Dynamically adding abstract methods to a class, or attempting to modify the
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abstraction status of a method or class once it is created, are not
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supported. The :func:`abstractmethod` only affects subclasses derived using
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regular inheritance; "virtual subclasses" registered with the ABC's
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:meth:`register` method are not affected.
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Usage::
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When :func:`abstractmethod` is applied in combination with other method
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descriptors, it should be applied as the innermost decorator, as shown in
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the following usage examples::
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class C(metaclass=ABCMeta):
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@abstractmethod
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def my_abstract_method(self, ...):
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...
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@classmethod
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@abstractmethod
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def my_abstract_classmethod(cls, ...):
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...
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@staticmethod
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@abstractmethod
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def my_abstract_staticmethod(...):
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...
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@property
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@abstractmethod
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def my_abstract_property(self):
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...
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@my_abstract_property.setter
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@abstractmethod
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def my_abstract_property(self, val):
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...
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@abstractmethod
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def _get_x(self):
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...
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@abstractmethod
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def _set_x(self, val):
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...
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x = property(_get_x, _set_x)
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In order to correctly interoperate with the abstract base class machinery,
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the descriptor must identify itself as abstract using
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:attr:`__isabstractmethod__`. In general, this attribute should be ``True``
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if any of the methods used to compose the descriptor are abstract. For
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example, Python's built-in property does the equivalent of::
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class Descriptor:
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...
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@property
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def __isabstractmethod__(self):
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return any(getattr(f, '__isabstractmethod__', False) for
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f in (self._fget, self._fset, self._fdel))
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.. note::
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@@ -177,6 +216,8 @@ It also provides the following decorators:
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...
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.. versionadded:: 3.2
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.. deprecated:: 3.3
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Use :class:`classmethod` with :func:`abstractmethod` instead
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.. decorator:: abstractstaticmethod(function)
@@ -192,18 +233,19 @@ It also provides the following decorators:
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...
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.. versionadded:: 3.2
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.. deprecated:: 3.3
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Use :class:`staticmethod` with :func:`abstractmethod` instead
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.. decorator:: abstractproperty(fget=None, fset=None, fdel=None, doc=None)
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A subclass of the built-in :func:`property`, indicating an abstract property.
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Using this function requires that the class's metaclass is :class:`ABCMeta` or
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is derived from it.
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A class that has a metaclass derived from :class:`ABCMeta` cannot be
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instantiated unless all of its abstract methods and properties are overridden.
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The abstract properties can be called using any of the normal
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'super' call mechanisms.
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Using this function requires that the class's metaclass is :class:`ABCMeta`
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or is derived from it. A class that has a metaclass derived from
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:class:`ABCMeta` cannot be instantiated unless all of its abstract methods
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and properties are overridden. The abstract properties can be called using
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any of the normal 'super' call mechanisms.
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Usage::
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@@ -220,6 +262,9 @@ It also provides the following decorators:
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def setx(self, value): ...
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x = abstractproperty(getx, setx)
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.. deprecated:: 3.3
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Use :class:`property` with :func:`abstractmethod` instead
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.. rubric:: Footnotes
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‎Doc/whatsnew/3.3.rst‎

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@@ -352,6 +352,23 @@ curses
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(Contributed by Iñigo Serna in :issue:`6755`)
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abc
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---
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Improved support for abstract base classes containing descriptors composed with
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abstract methods. The recommended approach to declaring abstract descriptors is
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now to provide :attr:`__isabstractmethod__` as a dynamically updated
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property. The built-in descriptors have been updated accordingly.
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* :class:`abc.abstractproperty` has been deprecated, use :class:`property`
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with :func:`abc.abstractmethod` instead.
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* :class:`abc.abstractclassmethod` has been deprecated, use
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:class:`classmethod` with :func:`abc.abstractmethod` instead.
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* :class:`abc.abstractstaticmethod` has been deprecated, use
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:class:`property` with :func:`abc.abstractmethod` instead.
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(Contributed by Darren Dale in :issue:`11610`)
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faulthandler
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------------
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‎Include/object.h‎

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@@ -473,6 +473,7 @@ PyAPI_FUNC(int) PyObject_HasAttrString(PyObject *, const char *);
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PyAPI_FUNC(PyObject *) PyObject_GetAttr(PyObject *, PyObject *);
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PyAPI_FUNC(int) PyObject_SetAttr(PyObject *, PyObject *, PyObject *);
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PyAPI_FUNC(int) PyObject_HasAttr(PyObject *, PyObject *);
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PyAPI_FUNC(int) _PyObject_IsAbstract(PyObject *);
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PyAPI_FUNC(PyObject *) _PyObject_GetAttrId(PyObject *, struct _Py_Identifier *);
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PyAPI_FUNC(int) _PyObject_SetAttrId(PyObject *, struct _Py_Identifier *, PyObject *);
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PyAPI_FUNC(int) _PyObject_HasAttrId(PyObject *, struct _Py_Identifier *);

‎Lib/abc.py‎

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@@ -26,7 +26,8 @@ def my_abstract_method(self, ...):
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class abstractclassmethod(classmethod):
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"""A decorator indicating abstract classmethods.
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"""
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A decorator indicating abstract classmethods.
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Similar to abstractmethod.
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@@ -36,6 +37,9 @@ class C(metaclass=ABCMeta):
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@abstractclassmethod
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def my_abstract_classmethod(cls, ...):
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...
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'abstractclassmethod' is deprecated. Use 'classmethod' with
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'abstractmethod' instead.
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"""
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__isabstractmethod__ = True
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class abstractstaticmethod(staticmethod):
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"""A decorator indicating abstract staticmethods.
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"""
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A decorator indicating abstract staticmethods.
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Similar to abstractmethod.
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@@ -56,6 +61,9 @@ class C(metaclass=ABCMeta):
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@abstractstaticmethod
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def my_abstract_staticmethod(...):
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...
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'abstractstaticmethod' is deprecated. Use 'staticmethod' with
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'abstractmethod' instead.
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"""
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__isabstractmethod__ = True
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class abstractproperty(property):
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"""A decorator indicating abstract properties.
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"""
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A decorator indicating abstract properties.
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Requires that the metaclass is ABCMeta or derived from it. A
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class that has a metaclass derived from ABCMeta cannot be
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def getx(self): ...
8998
def setx(self, value): ...
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x = abstractproperty(getx, setx)
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'abstractproperty' is deprecated. Use 'property' with 'abstractmethod'
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instead.
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"""
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__isabstractmethod__ = True
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‎Lib/numbers.py‎

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@@ -5,7 +5,7 @@
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TODO: Fill out more detailed documentation on the operators."""
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8-
from abc import ABCMeta, abstractmethod, abstractproperty
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from abc import ABCMeta, abstractmethod
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__all__ = ["Number", "Complex", "Real", "Rational", "Integral"]
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"""True if self != 0. Called for bool(self)."""
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return self != 0
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53-
@abstractproperty
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@property
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@abstractmethod
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def real(self):
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"""Retrieve the real component of this number.
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This should subclass Real.
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"""
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raise NotImplementedError
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@abstractproperty
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@property
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@abstractmethod
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def imag(self):
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"""Retrieve the imaginary component of this number.
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__slots__ = ()
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@abstractproperty
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@property
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@abstractmethod
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def numerator(self):
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raise NotImplementedError
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279-
@abstractproperty
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@property
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@abstractmethod
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def denominator(self):
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raise NotImplementedError
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