Terry Reedy <tjre...@udel.edu> writes: >> What happens then is you define a new interface. > Like key= versus cmp=
Well, in an untyped language like Python, adding a feature to an interface doesn't require defining a new interface unless you change something incompatibly. key= is very useful but it can be added without breaking cmp= . > 2to3 could probably gain a fixer to change > .sort(cmp=f) # to > > import functools import cmp_to_key > .sort(key=functools.cmp_to_key(f)) > > I know some would not like this because interface change is not their > real concern. Looks like a good idea. There is an efficiency hit from the above in some situations, but at least it prevents code from breaking, so unless there's some drawback I'm not currently spotting, it's better than nothing and I'd endorse adding such a wrapper. 2to3 should show some kind of diagnostic and maybe put a comment into the output code, when it does that particular transformation, since most of the time there's probably a better way to write the key function. -- http://mail.python.org/mailman/listinfo/python-list
