In Squeak, what is the cost of using an accessor vs. a direct call to the
ivar?  In VisualAge, for example, the compiler optimizes a send to an
accessor and makes it equivalent to a direct access.  At least, I believe it
is - I'll have to run tests to verify.  I think this is true with other
dialects as well.

Jeff Odell

----- Original Message -----
From: Carl Gundel <morphic at hotmail.com>
To: <squeak at cs.uiuc.edu>
Sent: Saturday, July 31, 1999 1:03 PM
Subject: re: Please use accessors!


> >From: Alan Lovejoy <sourcery at pacbell.net>
> >Reply-To: squeak at cs.uiuc.edu
> <big snip>
> >8. Given the above, I would avoid being dogmatic on this
> >issue.  I think the fact that so many good Smalltalk programmers
> >still access instance variables directly, and that code that commits
> >this "sin" has lasted unchanged for so long, should cause one to
> >at least question whether or not it's all that sinful.
> <snip>
>
> Thanks for the brain dump Alan!  :-)
>
> I understand the pragmatics of this issue well, but I feel compelled to
make
> a counterpoint about the above.  Code that accesses ivars directly can be
> brittle.  In particular, code which uses both direct access and accessor
> methods on the same ivars can behave in unpredictable ways.  Sometimes
such
> code survives for a very long time because it is brittle and hard to
> understand, and no one wants to touch it for fear of breaking it.
>
> I tend to defer writing code which accesses ivars directly until
performance
> tuning time.  I wish I never had to write such code because it hurt the
> maintainability and extensibility of my design, but I live in the real
world
> (oh Bah!).
>
> Thanks again!
>
> -Carl
>
>
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