any() and all() Was: Pre-PEP: Dictionary accumulator methods
Py2.5 is already going to include any() and all() as builtins. The signature does not include a function, identity or otherwise. Instead, the caller can write a listcomp or genexp that evaluates to True or False: any(x = 42 for x in data) [Roose] Oh great, I just saw that. . . . But I wish it could be included in Python 2.4.x. If it is any consolation, the any() can already be expressed somewhat cleanly and efficiently in Py2.4 with genexps: True in (x = 42 for x in data) The translation for all() is a little less elegant: False not in (x = 42 for x in data) Raymond Hettinger -- http://mail.python.org/mailman/listinfo/python-list
any() and all() Was: Pre-PEP: Dictionary accumulator methods
[Roose] Actually I was just looking at Python 2.5 docs since you mentioned this. http://www.python.org/dev/doc/devel/whatsnew/node3.html It says min() and max() will gain a key function parameter, and sort() gained one in Python 2.4 (news to me). It also appears in itertools.groupby() and, for Py2.5, in heapq.nsmallest() and heapq.nlargest(). And they do indeed default to the identity in all 3 cases, so this seems very inconsistent. If one of them has it, and sort gained the argument even in Python 2.4 with generator expressions, then they all should have it. any(x = 42 for x in data) Not to belabor the point, but in the example on that page, max(L, key=len) could be written max(len(x) for x in L). Think about it. A key= function is quite a different thing. It provides a *temporary* comparison key while retaining the original value. IOW, your re-write is incorrect: L = ['the', 'quick', 'brownish', 'toad'] max(L, key=len) 'brownish' max(len(x) for x in L) 8 Remain calm. Keep the faith. Guido's design works fine. No important use cases were left unserved by any() and all(). Raymond Hettinger -- http://mail.python.org/mailman/listinfo/python-list
Re: any() and all() Was: Pre-PEP: Dictionary accumulator methods
Ah OK, I stand corrected. Whoops. I just read the web page and thought the wrong thing, that makes sense. Think about it. A key= function is quite a different thing. It provides a *temporary* comparison key while retaining the original value. IOW, your re-write is incorrect: L = ['the', 'quick', 'brownish', 'toad'] max(L, key=len) 'brownish' max(len(x) for x in L) 8 Remain calm. Keep the faith. Guido's design works fine. No important use cases were left unserved by any() and all(). Raymond Hettinger -- http://mail.python.org/mailman/listinfo/python-list
