Re: AI12-0218: What is the portable representation clause for processing IETF packets on little-endian machines?

["Randy Brukardt" <randy@rrsoftware.com>]

"Dan'l Miller" <optikos@verizon.net> wrote in message 
news:5c9b9f90-884f-4de7-8663-d39a67949f4f@googlegroups.com...
>* on a per-processor, per-toolchain basis, selected via the conditional 
>compilation
>via the C preprocessor.  This selection (out of nonportable categorization) 
>is
>what accomplishes the portability.  Ada has no equivalent other than
>AI32-0218's/GNAT's solution.

The best way to do this in Ada is with different package bodies (and 
sometimes specs) for each target. That's how Janus/Ada is designed, and it 
works great. I know the GNAT project system even has facilities to make this 
happen automatically (by selecting the unit to compile based on a version 
id).

The problem is that existing version control systems cannot handle such 
designs properly. That was definitely true in the late 1980's (so I designed 
a wrapper around our version control to deal with this), and I haven't seen 
any that deal with it properly to date. (The main issue being that when a 
bug is fixed in one such package, you want a notification to check if the 
same is needed for the other versions. No version control that I'm aware of 
can handle this - they all seem focused on merging development for a single 
end-product.)

Shortcomings in version control are way outside of anything that the 
language can control. And using a sub-optimal design because ancillary tools 
are broken seems to be letting the tail wag the dog.

                 Randy.