On Wed, Aug 13, 2008 at 10:49 PM, Carl Banks <[EMAIL PROTECTED]> wrote: >> There is no point of nested classes because nested classes _are not_ >> supported by python. They are simply an artifact of not actively >> denying the syntax non-globally. I would fully support a change to the >> language to actively forbid a class definition that is not >> module-level. > > I think that's taking it a little too far. It's not unreasonable to > throw small, private use classes into the class definition, like so: > > class Someting(object): > class PrivateException(Exception): > pass > > And inside function a class definition can make a lot of sense. > Oftentimes I write a quick adaptor class because I want to pass > something to code that expects something else, for instance: > > def some_function(lines): > class FileMimicker(object): > def __init__(self): > self.index = 0 > def readline(self): > line = lines[self.index] > self.index += 1 > return line > function_that_calls_readline(FileMimicker()) > > > (Why would I want to clutter up my module's namespace for that silly > thing?) > > So I see no good reason for the compiler to disallow nested class > statements; it's occasionally useful and not a common pitfall. > > Carl Banks
I know every rule has its exceptions. I put "don't nest classes" in with other similar rules I will claim, where I think its safest to say "Never do this!", because only then will you know that, should you actually do it at some point, you've got a reason good enough to break a "rule". As for the cluttering of the namespace, I don't buy it. Sure there are cases to be made to reduce the number of names in any scope, but I don't see a big advantage here. Its still accessible from the module, just though the class. I also don't see any examples of nested classes that wouldn't be useful elsewhere, your example included. For that matter, your example should just being using StringIO. -- Read my blog! I depend on your acceptance of my opinion! I am interesting! http://techblog.ironfroggy.com/ Follow me if you're into that sort of thing: http://www.twitter.com/ironfroggy -- http://mail.python.org/mailman/listinfo/python-list
