consistency again ( was: Notation for delegation in OMT or BOOCH )

Bruce McKenzie bruce at
Tue Jul 19 23:46:53 UTC 1994

> [ deleted ]
> I found this work very interesting. One of the things I liked most
> was how message reception was devided into two phases: the lookup
> where the object ( really the meta-object, but let's ignore that )
> decides which of its slots is refered to by the message selector, and
> the apply where the result of the lookup does something according to
> its nature.

> [ more deleted ]

> I would not complicate the implementation for consistency unless there
> was a real gain. I can imagine some pretty useless stuff ( I suggested
> method parents about two years ago :-)  :

Background: I'm a near-lurker on this list. I do Objective-C
programming for the NeXT. One of the nicest aspects of Obj-C is the
(true) dynamic binding, and the run-time class creation, loading, and
general mayhem that is possible.

One benefit that I can see to the two-phase approach is the
possibility of implementing a conscience for an object. Namely,
"Normally, I implement all setPosition:: messages, but when the system
is in a 'panic' state, I ignore them." (implying that "setPosition::"
is a family of messages, and you don't want to put the same state
checking code in each one)

Objective-C provides capabilities to do this, but it would be a bit of
a hack.

Does this sound useful? Have people experimented with this?

Bruce McKenzie (spuds at, NeXTMail welcome)
Atlas Software Ventures, Inc.
PO Box 1299, Santa Clara, CA 95052-1299
800/278-9909 (ASV-9909)
*** Software Development, specializing in NEXTSTEP ***

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