Make a nested class definition inherit the attributes of the class in whose scope it was defined.

gistfile1.py

'''Make a nested class definition inherit the attributes of
the class in whose scope it was defined.
'''


class Context(object):
    '''Base type for Context objects.
    '''
    pass


class ChildContext(object):
    '''Special descriptor wrapper for child context
    classes.
    '''
    def __init__(self, member):
        self.member = member

    def __get__(self, obj, objtype):
        try:
            return self.child_type
        except AttributeError:
            pass
        member = self.member
        name = member.__name__
        attrs = dict(parent=obj, __metaclass__=ContextMeta)
        child_type = type(name, (member, objtype), attrs)
        self.child_type = child_type
        return child_type


class ContextMeta(type):
    def __new__(meta, name, bases, attrs):
        for attr, member in attrs.items():
            # Wrap any Context subclasses in ChildContext
            # descriptors.
            try:
                if issubclass(member, Context):
                    attrs[attr] = ChildContext(member)
            except TypeError:
                # The member wasn't a class object.
                continue
        return type.__new__(meta, name, bases, attrs)


class Context(Context):
    __metaclass__ = ContextMeta


class ContextMeta(type):
    '''Overwrite ContextMeta, which has already been invoked in
    all Context class definitions by this point, so that the
    ChildContext descriptor will have a valid metaclass subtype
    to use in subclassing the child context.
    '''
    __new__ = type.__new__


# And now to use it.
class Person(Context):
    def print_bio(self):
        print self.first_name, self.last_name, 'likes', self.fave_food


class Thom(Person):
    first_name = 'Thom'
    last_name = 'Neale'
    fave_food = 'mac n cheese'

    class Jacob(Person):
        first_name = 'Jacob'
        fave_food = 'grapes'


Thom().print_bio()
Thom().Jacob().print_bio()

import pdb; pdb.set_trace()
# This prints:
# Thom Neale likes mac n cheese
# Jacob Neale likes grapes