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[Help-smalltalk] Dynamic Message Dispatch???

From: Duke Normandin
Subject: [Help-smalltalk] Dynamic Message Dispatch???
Date: Sat, 23 Jan 2010 21:10:24 -0700 (MST)
User-agent: Alpine 2.01 (OSX 1266 2009-07-14)

Hello list...

Still haven't been able to compile GST from git sources ;( but life
goes one...

Currently Reading Alan Lovejoy's "Smalltalk: Getting The Message
The Essentials of Message-Oriented Programming with Smalltalk".

I'm not grokking this paragraph:

"Because of dynamic message dispatch, the semantics of sending a
message to an object depend absolutely on the object that receives the
message. The same message may be interpreted quite differently by
different objects, due to the fact that each object may use a
different method namespace in order to lookup a method based on the
selector of a message, and so may associate a different method with
the same message selector. Consequently, a message can be thought of
as an abstract function call which will result in the execution of
whatever concrete function (subroutine) is chosen by the object that
receives the message. The idea is that a message should name the
logical function to be computed, but the object receiving the message
should decide how best to physically compute the desired result. The
universal, pervasive application of this distinction between logical
function (semantics) and physical function (implementation strategy)
is the central point of object oriented programming, as defined and
envisioned by Dr. Kay."

Would one of you fine Smalltalkers explain the above in plain language
- 1 or 2 sentences would be good. I'm assuming that I _need_ to
understand what dynamic message dispatch means and how it works before
I can proceed intelligently. TIA...

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