Paul Moore wrote:
2009/3/2 Benjamin Peterson <benja...@python.org>:
2009/3/1 Paul Moore <p.f.mo...@gmail.com>:
Is it worth getting simplegeneric exposed in 3.1
(http://bugs.python.org/issue5135)? If it's going to be in 2.7, I'd
like to see it hit 3.1. The patch is against trunk (for 2.7) at the
moment, I'm not sure what the process would be for forward-porting it
(do I generate a new patch against the py3k branch, or should it be
applied to trunk and merged in?)
Patches to the trunk are fine.
OK, thanks.
As for the actual feature, I don't think it should hold up releases.
Fair enough.
Given that the purpose of 2.7 is
a) maintenance of existing code (which can include minor new features
for existing facilities), and
b) easing conversion of code to 3.1
I am puzzled at the idea of adding a new facility to 2.7 that would not
be in 3.1+. It would lock code into 2.7+ and counter purpose b).
The key problem with the patch is that ABCs do not play well with the
type of introspection required to implement a generic function -
namely enumeration of the superclasses of a class. The MRO of the
class is fine for normal inheritance, but for ABCs it is possible to
register classes which don't inherit from the ABC, so that you have a
situation where issubclass (C, MyABC) can be true without MyABC being
in C.__mro__:
I have no idea of what the solution should be other than your proposed
'document the limitations', but someone who has moved on to 3.x and is
only interested in generics would find it frustrating to be denied them
because of the existence of something else they are not using.
Terry Jan Reedy
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