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Re: objective-c: how slow ?

From: Marko Mikulicic
Subject: Re: objective-c: how slow ?
Date: Sat, 08 Sep 2001 01:00:11 -0400
User-agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.3) Gecko/20010801

Richard Frith-Macdonald wrote:

So, with delegation and object A which does not handle a particular
message, passes the message to a delegate object B which executes
the appropriate method, whereas with behaviors, A gets the method from
B and executes it itsself.

Sorry, its only a fact of terminology. I mistaken calling it "true"
as opposed to "not true". I'm grown up with this termin, and many people use it,
but it could be wrong or at least have different meanings.

The behavior mechanism is not directly supported by the language, and
is therefore dangerous in ObjC - since you need to be careful not to
take on any behavior which would try to work with instance variables
that don't exist in your object and cause a crash.  In other languages
where ivars are only accessed by methods, you just need to worry about
runtime exceptions, not actual crashes when you make a mistake.

I have a vision about OO language which certainly you won't share (You would be probably using smalltalk not objc), that instance variable must not be accessed directly, so that subclasses can overrive ivar access with some method. (for flexibility). The VM/runtime should optimize out actual unnecessary calls, but there must be the flexibility. I don't want to dispute OO desing here. I think I would not be using objc if there was not OpenStep. I think that NeXT guys created a very confortable framework (althrough when I first saw these loong method names I felt pain) where you can be very productive from the beginning. And objc doesn't need any new feature for OpenStep.


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