Issue with new-style classes and operators

[sismex01 at hebmex.com]

> From: Jan Decaluwe [mailto:jan at jandecaluwe.com]
> Sent: Monday, November 25, 2002 4:39 PM
> 
> Alex Martelli wrote:
> > 
> > So, to wrap an arbitrary object X in such a way that X's special
> > methods will be used by any operator, you need to ensure you do
> > the wrapping with a _class_ that exposes said special methods.
> > That's generally easiest to do with a factory function with a
> > nested class that uses inheritance, but you have many other choices
> > depending on what exactly you're trying to accomplish.
> 
> Mm, I think I see, thanks for that. (I'll try again to 
> understand this from the documentation.) However, if I use
> inheritance from an immutable type, the subtype is automatically
> immutable also, right?


Maybe not...
Mind you, I don't know why someone would want to do this.

>>> class MuTint(int):
	def __init__(self):
		self._items = {}
	def __getitem__(self, item):
		return self._items[item]
	def __setitem__(self, item, value):
		self._items[item] = value
	def __delitem__(self, item):
		del self._items[item]

		
>>> m = MuTint()
>>> m
0
>>> m["hello"] = 2
>>> m["goodbye"] = 3
>>> m
0
>>> print m
0
>>> m["hello"]
2



> So I wanted mutability, I'm back to delegation ... and apparently
> stuck with new-style classes ???
> 
> Jan

But what's to great about old-style classes?

-gustavo