Re: Message passing

[HENRY@MIT-AI (Sent by HENRY0@MIT-AI)]

    I'd like to make a suggestion for a change to the
    microcode for SELECT-METHODS which I think will 
    make them more general without signficant loss in efficiency. 
    Right now, the method to be invoked is selected by 
    doing an ASSQ-like search down the method list, using the
    first argument as a key. This means that a method must declare
    which symbols it responds to when you create the method. The
    method can't apply a function at run time to decide whether to 
    accept the message or let another method handle it. 
    What I'd like is another kind of entry in the method list, which
    supplies a predicate to be applied to the message [the &rest of the
    <- call] and if that predicate returns true, the method in that entry is 
    selected [called with the message as argument], 
    otherwise continue down the method list. 
    This is useful in many situations. For instance, it helps with 
    multiple superclass types of things, because a method can
    conditionally decide to accept a message based on whatever it
    wants, say its current viewpoint.
    What do you think?