On 2008-08-01, Matthew Fitzgibbons <[EMAIL PROTECTED]> wrote: > Antoon Pardon wrote: >> On 2008-08-01, Erik Max Francis <[EMAIL PROTECTED]> wrote: >>> Antoon Pardon wrote: >>> >>>> I now have the following question for people who argue that "if x" >>>> is more polymorphic. I could subclass list, so that instances >>>> of this new sequence would always behave as true, even if they are >>>> empty. I could then rewrite my loop as follows: >>>> >>>> while 1: >>>> extra = produce() >>>> if not extra: >>>> break >>>> for el in extra: >>>> adjust_with(el) >>>> calculate() >>>> >>>> Is this second loop now more polymorphic as the first? >>> It's more confusing since you've changed the standard behavior of a >>> standard type, which doesn't really have anything to do with >>> polymorphism. It's more confusing, if that's a benefit. >> >> So you accept my point that "if x" can be less polymorphic >> and in fact can be more confusing than a more specific test. >> > > I think your example is more related to a trap with polymorphism in > general rather than an argument against 'is x' specifically.
I didn't want to argue against "if x". I just wanted to give a counter point to the argument that "if x" is more polymorphic. Whether more or less polymorphic is good or bad, depends on what kind of polymophism and circumstances. -- Antoon Pardon -- http://mail.python.org/mailman/listinfo/python-list
