    class Role:
        """
        Roles are used in conjuction with RoleUser to provide role-based security.
        All roles have a name and a description and respond to playsRole().

        RoleUser also responds to playsRole() and is the more popular entry point
        for programmers. Application code may then do something along the lines of:

        if user.playsRole('admin'):
            self.displayAdminMenuItems()

        See also:
            * class HierRole
            * class RoleUser
        """

        ## Init ##

        def __init__(self, name, description=None):
            self._name = name
            self._description = description

        ## Attributes ##

        def name(self):
            return self._name

        def setName(self, name):
            self._name = name

        def description(self):
            return self._description

        def setDescription(self, description):
            self._description = description

        ## As strings ##

        def __str__(self):
            return str(self._name)

        def __repr__(self):
            return '<%s %r instance at %X>' % (self.__class__, self._name, id(self))

        ## The big question ##

        def playsRole(self, role):
            """ Returns true if the receiving role plays the role passed in. For Role, this is simply a test of equality. Subclasses may override this method to provide richer semantics (such as hierarchical roles). """
            assert isinstance(role, Role)
            return self==role