Demo: an object that after closed, is in invalid state. At this point, any method invocation will result in an exception unless that method is decorated. Output: http://codepad.org/BUssgQR3

closed_object_with_decorator.py

import functools


def accessible_while_closed(func):
    """
    A decorator to mark a function as available, even after the object
    closed.
    """
    func.accessible_while_closed = True
    return func


class MarkAsClosed(object):
    def _invalid_action(self, *args, **kwargs):
        raise IOError('object closed')

    def mark_as_closed(self):
        for name in dir(self):
            # Ignore private members
            if name.startswith('_'):
                continue
            member = getattr(self, name)
            # Ignore non-callable (i.e. data) members
            if not callable(member):
                continue
            # Ignore those callable members decorated with
            # accessible_while_closed
            if getattr(member, 'accessible_while_closed', False):
                continue
            setattr(self, name, self._invalid_action)


class Foo(MarkAsClosed):
    def close(self):
        print 'Foo.close'
        self.mark_as_closed()

    def do_something(self):
        print 'Foo.do_something'

    @accessible_while_closed
    def ok_when_closed(self, name):
        print 'Foo.ok_when_closed, name =', name


f = Foo()
f.close()
f.ok_when_closed('Hai')  # Should be OK
f.do_something()  # Not OK