[issue11610] Improving property to accept abstract methods

[Darren Dale]

Darren Dale <dsdale24 at gmail.com> added the comment:

On Sat, May 14, 2011 at 4:28 PM, Benjamin Peterson
<report at bugs.python.org> wrote:
>
> Benjamin Peterson <benjamin at python.org> added the comment:
>
> I still dislike the reduntancy of having abstractmethod and abstractproperty on a method. I think a better idea is having abstractproperty.abstract(getter/setter/deleter).

Right, but I explained why the redundancy is necessary in order to
preserve backwards compatibility. If the abstractproperty constructor
were changed to tag methods it receives as abstract, it would be a
backwards-incompatible change in behavior with potential consequences
for consumers of abstractproperty.
abstractproperty.abstract(getter/setter/deleter) could be implemented,
but it still wouldn't change the fact that if a getter/setter is
intended to be abstract, it needs to be decorated with @abstractmethod
before being passed to the abstractproperty() constructor. This is
true today in <=python-3.2: its not mentioned in the documentation,
but the behavior exists all the same.

Properties are composite objects, their behavior is defined by it is
the setters/getters/deleters they receive. So its actually a very
conceptually clean solution to decorate a method with @abstractmethod,
and it fits really nicely with the rest of the abc module. Why does
abstractproperty need special abstract(setter/getter/deleter) methods,
when the existing methods combine with @abstractmethod in a clean way
to produce the exact same result? To save one line of code?

Darren

----------

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue11610>
_______________________________________