New submission from Darren Dale <dsdal...@gmail.com>:
I posted a suggestion at python-ideas that the declaration of abstract
properties could be improved in such a way that they could be declared with
either the long-form or decorator syntax using the built-in property and
abc.abstractmethod:
{{{
class MyProperty(property):
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
for f in (self.fget, self.fset, self.fdel):
if getattr(f, '__isabstractmethod__', False):
self.__isabstractmethod__ = True
break
class C(metaclass=ABCMeta):
@MyProperty
@abstractmethod
def x(self):
pass
@x.setter
@abstractmethod
def x(self, val):
pass
# this syntax would also be supported:
#@abstractmethod
#def getx(self):
# pass
#@abstractmethod
#def setx(self, val):
# pass
#x = MyProperty(getx, setx)
class D(C):
'D does not define a concrete setter and cannot be instantiated'
@C.x.setter
def x(self):
return 1
class E(D):
'E has a concrete getter and setter, and can be instantiated'
@D.x.setter
def x(self, val):
pass
}}}
It is hopefully evident that a relatively minor extension can be made to the
built-in property such that @abstractproperty would no longer be needed. I have
prepared a patch, complete with documentation and unit tests, but unfortunately
I have not been able to test it because I have not been able to build Python
from a mercurial checkout on either Ubuntu 11.04 or OS X 10.6.6 (for reasons
unrelated to the patch.) BDFL thought the idea sounded good for inclusion in
Python-3.3, and requested I submit the patch here.
----------
components: Library (Lib)
files: property_with_abstractmethod.patch
keywords: patch
messages: 131436
nosy: dsdale24
priority: normal
severity: normal
status: open
title: Improving property to accept abstract methods
type: feature request
versions: Python 3.3
Added file: http://bugs.python.org/file21293/property_with_abstractmethod.patch
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue11610>
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