[issue11610] Improving property to accept abstract methods

[Benjamin Peterson]

Benjamin Peterson <benjamin at python.org> added the comment:

2011/5/14 Darren Dale <report at bugs.python.org>:
>
> 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.

I'm not suggesting that it tag methods it receives as abstract.
@getter/setter/deleter would still act the same.

> 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.

Why not? You could set the __abstractmethod__ attribute in abstractgetter().

> 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?

I find it produces a rather unfortunate ordering dependency for the
decorators which is hard to remember.

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