[Python-Dev] functools additions
So if it's alright with the privledged folk - I'd like to commit these minor (and probably non-controversial) additions to the functools module. def cat(x): return x def multimap(func, s, n=2): assert n > 0, "n must be positive" return (map(func, seq) if n == 1 else map(lambda x: multimap(func, x, n-1), seq)) def multifilter(func, s, n=2): return multimap(lambda x: filter(func, x), s, n-1) def multireduce(func, s, n=2): return multimap(lambda x: reduce(func, x), s, n-1) class nullfunc(object): def __call__(self, *a, **k): return self def __getattr(self, name): return getattr(None, name) cat is a generic identity function - useful for some higher-order functions to specify a function that "does nothing". multimap, multifilter, and multireduce, are all multi-dimensional versions of map, filter, and reduce. nullfunc is a special callable object that emulates the failed callable None proposal - which wasn't really a good idea, but would have been more useful as a different object apart from None. you could probably even put cat in __builtins__ - so you don't need to waste effort importing such a trivial function. --. "What's money? A man is a success if he gets up in the morning and goes to bed at night and in between does what he wants to do." ~ Bob Dylan ___ Python-Dev mailing list [EMAIL PROTECTED] http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] functools additions
> So if it's alright with the privledged folk - I'd like to commit > these minor (and probably non-controversial) additions to the functools > module. Do you have commit access? What's your real name? -1 on these additions. If lambda x:x would be added, it should be named "identity", not "cat" (if that name is meant to raise associations with the Unix cat(1) utility, please understand that "cat" is short for "concatenate"). Regards, Martin ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] functools additions
Do you have commit access? What's your real name? I prefer to remain pseudonymous, and I don't have commit access. Yeah... they're not terribly useful - more or less there for the sake of being there. Batteries included and all that ...but now I've got a more useful idea for a function wrapper around predicate functions to make them a little more functionally inclined. Something like... @predicate def hasnext(x): return hasattr(x, "next") @predicate def hasiter(x): return hasattr(x, "__iter__") isiterable = hasnext or hasiter #or/and/not operators construct new predicate functions isEmptyIterable = isiterable and not predicate(bool) isgenerator = isiterable and (lambda x: hasattr(x, "send") and hasattr(x, "throw")) filter(isgenerator or callable, SomeSequence) -- "What's money? A man is a success if he gets up in the morning and goes to bed at night and in between does what he wants to do." ~ Bob Dylan ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] functools additions
> def cat(x): return x > > def multimap(func, s, n=2): > assert n > 0, "n must be positive" > return (map(func, seq) > if n == 1 else > map(lambda x: multimap(func, x, n-1), > seq)) > > def multifilter(func, s, n=2): > return multimap(lambda x: filter(func, x), s, n-1) > > def multireduce(func, s, n=2): > return multimap(lambda x: reduce(func, x), s, n-1) > > class nullfunc(object): > def __call__(self, *a, **k): return self > def __getattr(self, name): return getattr(None, name) Could you describe what these functions do? Preferably with examples that demonstrates that they are useful. -- mvh Björn ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
Re: [Python-Dev] functools additions
On Sun, 15 Apr 2007 18:18:16 -0400, SevenInchBread <[EMAIL PROTECTED]> wrote: >>>Do you have commit access? What's your real name? >I prefer to remain pseudonymous, and I don't have commit access. > >Yeah... they're not terribly useful - more or less there for the sake of >being there. Batteries included and all that > Please discuss this on the python-ideas list before bringing it up on python-dev. Jean-Paul ___ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
