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From: =?UTF-8?Q?Bj=c3=b6rn_Lundin?= <b.f.lundin@gmail.com>
Newsgroups: comp.lang.ada
Subject: Re: AI12-0218: What is the portable representation clause for
 processing IETF packets on little-endian machines?
Date: Sat, 12 May 2018 12:33:18 +0200
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Xref: reader02.eternal-september.org comp.lang.ada:52312
Date: 2018-05-12T12:33:18+02:00
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On 2018-05-12 00:12, Randy Brukardt wrote:
> 
> The best way to do this in Ada is with different package bodies (and 
> sometimes specs) for each target. 

We do this too.


> The problem is that existing version control systems cannot handle such 
> designs properly. 

To get around that we have subdirectories matching the target

-w32_x86
-lnx_x64
-aix_ppc

each of these directories would contain the native body and spec for the
platform. Each directory and file is version_controlled.

The build system (first homebrew, now gpr) only includes the directory
matching the correct target. So when building on AIX, the compiler never
sees the directories lnx_x64 not w32_x86.

Each platform tests on an environment variable we set that has one of
the above 3 values.

So in essence we limit the files the compiler sees to the ones
belonging to the current platform.


-- 
--
Björn