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From: Robert Dewar <robert_dewar@my-deja.com>
Subject: Re: A question to the "access-type lifetime rule"
Date: 2000/04/03
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References: <38E89AB9.7D33E88C@hamilton.physik.uni-konstanz.de>
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In article <38E89AB9.7D33E88C@hamilton.physik.uni-konstanz.de>,
  bernd.rinn@uni-konstanz.de wrote:

> I want to write an numerical integration function, that is
> defined in a separate package as

This is a classical case where the use of a generic is far
preferable from every point of view. Forget about pointers
to subprograms completely, this is not what they are for
in Ada!

Nested functions and pointers-to-functions do not go well
together. That is why C, C++, Ada and many other languages
avoid this combination.

Ada 95 allows the combination but restricts it to be safe.

GNAT+Unrestricted_Access and GNU C allow the unrestricted
combination, but this is definitely programmer-beware
territory since dangling procedure pointers are about
as horrible a disaster as one can imagine.


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