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From: Robb.Nebbe@di.epfl.ch (Robb Nebbe)
Newsgroups: comp.lang.ada
Subject: Re: C++ to Ada95, help please
Date: 22 Mar 1995 11:38:24 GMT
Organization: Ecole Polytechnique Federale de Lausanne
Sender: nebbe@lglsun3.epfl.ch (Robb Nebbe)
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Date: 1995-03-22T11:38:24+00:00
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In article <D5tIGu.Cn6@inmet.camb.inmet.com>, stt@henning.camb.inmet.com (Tucker Taft) writes:

|> 
|> I believe GNAT supports a pragma "Unchecked_Union" (approximately) which
|> is applied to a discriminated record to make it look like a C
|> union.  The basic model is that a C union is essentially an undiscriminated
|> variant record.  The pragma requests the compiler to omit the
|> discriminant in memory, though it still exists "conceptually."

The solution I have used is to declare each variant as a separate type
and use a rep clause for the size. Then I use Unchecked_Conversion to
change between views.

It seems to me that the Unchecked_Union pragma would be a better solution
if the compiler provides it.

Robb Nebbe