copysort patch, was RE: [Python-Dev] inline sort option

Tue Oct 28 12:42:16 EST 2003

> Hmmm... maybe one COULD make a custom descriptor that does support
> both usages... and maybe it IS worth making the .sorted (or whatever name)
> entry a case of exactly such a subtle custom descriptor...

Thanks for the idea, I can use this as a perverted example in my talk
at Stanford tomorrow. Here it is:
import new
def curry(f, x, cls=None):
 return new.instancemethod(f, x)
class MagicDescriptor(object):
 def __init__(self, classmeth, instmeth):
 self.classmeth = classmeth
 self.instmeth = instmeth
 def __get__(self, obj, cls):
 if obj is None:
 return curry(self.classmeth, cls)
 else:
 return curry(self.instmeth, obj)
class MagicList(list):
 def _classcopy(cls, lst):
 obj = cls(lst)
 obj.sort()
 return obj
 def _instcopy(self):
 obj = self.__class__(self)
 obj.sort()
 return obj
 sorted = MagicDescriptor(_classcopy, _instcopy)
class SubClass(MagicList):
 def __str__(self):
 return "SubClass(%s)" % str(list(self))
unsorted = (1, 10, 2)
print MagicList.sorted(unsorted)
print MagicList(unsorted).sorted()
print SubClass.sorted(unsorted)
print SubClass(unsorted).sorted()
--Guido van Rossum (home page: http://www.python.org/~guido/)