Re: reinitialization protocol

[Danny Bobrow <Bobrow.pa@Xerox.COM>]

    > ;;; Generic functions for managing the dependents of an
    object.  This is

    Perhaps this is in the mop document, but, can you give a short,
    high level description of what exactly a "dependent" is? With an
    example? I briefly looked over my back mail and couldn't find
    anything. Thanks.
The concept of dependent is not in the document that you received.  Patrick and
Dave suggested at the Cambridge meeting that only some subclasses of a given
class need be updated when the class changes (A class that never has had its
inheritance finalized need not be updated).  They suggested that a subclass
could register itself with a superclass when it wanted to be notified of changes
to that superclass.  

The generalization is as follows.  An object O2 is dependent on O1 if it
registers itself as such.  The intent is that O2 will be notified if O1 changes
in certain ways.  Of course, methods on O1 must cooperate to the extent that
they call update-dependent for each dependent, but they need not know anything
about what update-dependent will do to O2. This use of registered dependents has
had a long and successful history in Smalltalk in their model view controller
paradigm, where views are dependents on the objects they are viewing.