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From: Robert Dewar <robert_dewar@my-deja.com>
Subject: Re: C/C++ programmer giving Ada95 a chance -- writing an emulator.
Date: 2000/04/01
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In article <38E2DC8A.45AE7226@research.canon.com.au>,
  Geoff Bull <geoff@research.canon.com.au> wrote:

> I don't think it is any clearer or better than my original.

I disagree, the use of general access-to-procedure values is
far less reliable, and has far less constrained semantics. The
use of explicit access-to-procedure values suffers from much
of the same problems as gotos.

Just as we prefer to replace a network of gotos with a case
statement, we prefer to replace the use of access-to-procedure
with dynamic dispatching where possible for many reasons.

As you note, there is very rarely any significant penalty for
this and this transformation is in fact a very nice example.

The version with tagged types is a little more complex
semantically, and that does have to be taken into
consideration.


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