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From: dewar@merv.cs.nyu.edu (Robert Dewar)
Subject: Re: how to pass access string across pragma C interface?
Date: 1997/06/23
Message-ID: <dewar.867078965@merv>#1/1
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References: <866734587.8496@dejanews.com>
 <01bc7f0c$494ab860$428371a5@dhoossr.iquest.com>
Organization: New York University
Newsgroups: comp.lang.ada
Date: 1997-06-23T00:00:00+00:00
List-Id: <comp.lang.ada>


David says

<<Assuming that the bit pattern for an access value and a C pointer are
identical on your
platform (this assumption is implicit in your interface pragma), then you
should
do something like:
buffer : string_access_type := new string (1 .. 2048);
>>


It is reasonable to assume that pointers to constrained array types are
easily mapped to C pointers, but it is asking for trouble to pass
pointers to unconstrained types. That is because the bounds information
must be somehow present, and C cannot know anything about it.

Thus code that passes such pointers to C, and even more code that receives
such pointers FROM C, is liable to be highly implementation dependent.