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From: Lutz Donnerhacke <lutz@iks-jena.de>
Newsgroups: comp.lang.ada
Subject: Re: Ideas for Ada 200X
Date: Tue, 3 Jun 2003 12:13:51 +0000 (UTC)
Organization: IKS GmbH Jena
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Date: 2003-06-03T12:13:51+00:00
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* Marin David Condic wrote:
> Lutz Donnerhacke wrote:
>> Yes, that's the Ada way. But for a lot of simple functions over simple data
>> types, defining such procedures is a pain.
>
> A question comes to mind: Is there any reason why a compiler cannot
> recognize "A := A + B;" as a special case and create an optimized
> solution equivalent to "A += B;"? A second question is: If they can
> detect and optimize this, are there any compilers that do so?

There are compilers which detect and optimize this.

> A third question is: Supposing the syntax were added - would any
> compilers start generating the optimized answer? It isn't at all clear to
> me that adding such syntax is going to get compilers to do a better job
> than they might already be doing.

The real question is not about optimizing.
The real question is about readablility and clear expression.

This is especially important, if X is an expression with side effects.
So evaluating X twice results in different variables. This is clearly not
the intent of the programmer and cause of errors, Ada is not famous for.

> It might be interesting to see of Gnat generates substantially different
> code for the Ada expression than it does for the C expression.

Try out an iterator access to see, what's interesting here.