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From: jfh@rpp386.cactus.org (John F Haugh II)
Newsgroups: comp.sources.d
Subject: Re: Help define Environment: usage in c.s.m
Message-ID: <19359@rpp386.cactus.org>
Date: 5 Jun 91 01:23:21 GMT
References: <1991May26.041741.22210@sparky.IMD.Sterling.COM> <2088:Jun309:46:2191@kramden.acf.nyu.edu>
Organization: River Parishes Programming, Austin TX
Lines: 40

In article <2088:Jun309:46:2191@kramden.acf.nyu.edu>, brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:
> I don't think the point of an Environment line is to express exactly
> which systems the package will run under. What's important is that it
> say where the package *won't* run, so that people avoid downloading the
> package if they won't be able to use it. So:
> 
> Environment: !SunOS<3.4, !SVR<3, !(Motif 1.1 & X11R3), ?!UNIX

The abundance of !'s in your examples lead me to believe that you've
not thought about this very hard.  This seems like an argument saying
the primary arithimetic operation is subtraction, therefore we will
always specify operations as subtractions, starting with 2 - (0 - 2) = 4.

What is clear is that the Environment: header must =concisely= state
what the environment is required to be (or not to be ...).  That is,
if BSD is straight out, the most concise expression would be

	Environment: !BSD

Whereas if just about any POSIX compliant UNIX with BSD enhancements
is likely to work, it would be

	Environment: POSIX && BSD

not some obfuscated

	Environment: !(! POSIX || !BSD)

> Similarly, pure-Sun packages would have Environment: !!SunOS. Packages
> for just Suns and SGIs would have Environment: !(!SunOS & !SGI). Most of
> my packages would have Environment: !(!BSD-derived).

as the above cited example leads one to suspect it may become ...

Remember, the goal is to be =human= readable, not =machine= readable.
-- 
John F. Haugh II        | Distribution to  | UUCP: ...!cs.utexas.edu!rpp386!jfh
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