#
# This file contains the Python code from Program 5.2 of
# "Data Structures and Algorithms
# with Object-Oriented Design Patterns in Python"
# by Bruno R. Preiss.
#
# Copyright (c) 2003 by Bruno R. Preiss, P.Eng.  All rights reserved.
#
# http://www.brpreiss.com/books/opus7/programs/pgm05_02.txt
#
class abstractmethod(object):

    def __init__(self, func):
	assert inspect.isfunction(func)
        self._func = func

    def __get__(self, obj, type):
        return self.method(obj, self._func, type)

    class method(object):

        def __init__(self, obj, func, cls):
            self._self = obj
            self._func = func
            self._class = cls
            self.__name__ = func.__name__

        def __call__(self, *args, **kwargs):
            msg = "Abstract method %s of class %s called." % (
                    self._func.__name__, self._class.__name__)
            raise TypeError, msg