[Python-Dev] ABC issues

[Raymond Hettinger]

From: "Armin Ronacher" <armin.ronacher at active-4.com>
> If the ABCs exists only for forward compatibility they will be mostly useless
> for every day usage.  

The Mapping ABC is still useful as a mixin in code that will run
on both 2.6 and 3.0.  It is the easiest way to start coding with views.


>> Deque's do not support count(), insert() or __iadd__().
>> They should not be registered.  

> If it doesn't implement the MutableSequence protocol it still is a Sized
> container.  However currently it's not registered as a container.

Seems useless to me.  I don't think the intent of the ABC pep was
to mandate that every class that defines __len__ must be registered
as Sized. 

> Another issue is that builtin types don't accept ABCs currently.  For example
> set() | SomeSet() gives a TypeError, SomeSet() | set() however works.

Pandora's Box -- sure you want to open it?


Raymond