[Python-Dev] Re: Guido's Magic Code was: inline sort option

Thu Oct 30 12:39:48 EST 2003

> Darn -- it WOULD be better in some cases if one could ONLY call
> a method on the class, NOT on an instance when the call would in
> any case ignore the instance. Calling dict.fromkeys(L3) is wonderful,
> the problem is that you can also call it on a dict instance, and THAT
> gets confusing. Similarly, calling list.sorted(iterable) is wonderful,
> but calling it on a list instance that gets ignored, L1.sorted(iterable),
> could perhaps be confusing.

Then why don't you use a custom descriptor which raises an exception
when an instance is passed in? Like:
 def __get__(self, obj, cls):
 if obj is None:
 return new.instancemethod(self.classmeth, cls)
 else:
 raise TypeError, \
 "Calling %s on instance %s ignores instance" % \
 (self.classmeth, obj)
-- 
Christian Tanzer http://www.c-tanzer.at/