On Tue, Aug 18, 2009 at 3:47 PM, David<davidsh...@googlemail.com> wrote: > Hi all, > > I'm trying to understand how scopes work within a class definition. > I'll quickly illustrate with an example. Say I had the following class > definition: > > class Abc: > message = 'Hello World' > > def print_message(self): > print message > >>>> instance = Abc() >>>> instance.print_message() > NameError: global name 'message' not defined > > My question is, why? message is not defined in print_message, but it > is defined in the enclosing scope (the class)?
A class' scope is never consulted when resolving variable names in its methods. The scopes consulted are roughly (and in this order): 1. Local variable scope (i.e. of the current function/method) 2. Enclosing functions (if you have functions nested inside other functions) 3. Globals (i.e. module-level variables) 3. Builtins (i.e. the built-in functions and methods, such as len()) To access class-level variables from within instance methods of the class, you have 2 options: A. Use the class name, i.e. Abc.message B. Reference the class indirectly, i.e. self.__class__.message Cheers, Chris -- http://blog.rebertia.com -- http://mail.python.org/mailman/listinfo/python-list
