From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-0.8 required=5.0 tests=BAYES_00,INVALID_DATE
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,ff4487ffe32cc5a4,start
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 1994-09-23 19:02:50 PST
Path: 
 bga.com!news.sprintlink.net!howland.reston.ans.net!usc!nic-nac.CSU.net!charnel.ecst.csuchico.edu!yeshua.marcam.com!MathWorks.Com!usenet.eel.ufl.edu!news.uoregon.edu!cs.uoregon.edu!usenet.ee.pdx.edu!fastrac.llnl.gov!lll-winken.llnl.gov!winken.llnl.gov!WOODRUFF
From: WOODRUFF@ec2226.addvax.llnl.gov
Newsgroups: comp.lang.ada
Subject: Package Interface, and interoperbility
Date: 23 Sep 94 15:53:16
Organization: Lawrence Livermore National Lab
Distribution: comp
Message-ID: <WOODRUFF.94Sep23155316@ec2226.addvax.llnl.gov>
NNTP-Posting-Host: ec2226.llnl.gov
Date: 1994-09-23T15:53:16+00:00
List-Id: <comp.lang.ada>

I have been studying the package Interface and I am puzzled about how
Ada implementations will be able to interface with other languages in
one specific situation.  I'm probably overlooking some important feature
so I hope somebody will enlighten me.

I learn in Interface.C.Pointer that I can instantiate that package and
then I will have a type Pointer that will let me link a C library that
has data of type Element * on its interface.  

My concern is that this appears to assume that *every* C implementation
uses the same representation for Element *.   Otherwise I think some
C-compiled library will not be callable from my Ada program because the
C compiler used a representation for Element * that disagrees with the
Ada compiler's code.  What's worse, one library will be fine and another
(compiled with a different C compiler) will be unusable, and I won't
know before I spend MY OWN MONEY (tm) on the library that I'm in
trouble. 

Is there reason for concern here? 

John