[Python-Dev] metaclass insanity

[Guido van Rossum]

>  > Can someone provide a reason why you'd want to use nested classes?
>  > I've never felt this need myself.  What are the motivations?
> 
> XIST (http://www.livinglogic.de/Python/xist/) uses nested classes
> to map XML element types and their attributes to Python classes.
> For example the HTML element type img looks like this in XIST:
> 
> class img(Element):
>     class Attrs(Element.Attrs):
>        class src(URLAttr): required = True
>        class alt(TextAttr): required = True
>        class align(TextAttr): values = ("top", "middle", ...)

That's cool.

--Guido van Rossum (home page: http://www.python.org/~guido/)