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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Standard Ada Preprocessor
Date: Thu, 29 Jan 2004 17:19:09 -0600
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Date: 2004-01-29T17:19:09-06:00
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"Warren W. Gay VE3WWG" <warren@ve3wwg.tk> wrote in message
news:qQbSb.57519$Kg6.643416@news20.bellglobal.com...
> Randy Brukardt wrote:
...
> > Different problem. We're trying to get the code to run unmodified on as
many
> > targets as possible. Having it being self-adapting is very valuable in
that
> > aim. (Hopefully, even the binarys can run on most targets unmodified.)
> >
>
> This is like probing hardware when Linux boots. Hardware is
> getting better, so that probes don't hang etc., but this adds
> time to the boot process, and for some hardware configs, is
> unstable and leads to hangs.
>
> Testing a version of a Linux kernel for a working asynch I/O
> API or not, seems much like the same thing. Its ugly, its
> dangerous and leads to more problems than it solves. It is
> much better to work all of that out at compile time, and never
> deal with it again.

I would be likely to base the decision whether or not to use a feature (say
asynch I/O) on the version information provided by the kernel. (I'm
presuming that Linux isn't so primitive that it doesn't have
version/distribution/supported features queries.) Plus, of course, lots of
upfront testing. Thus, the same info that you're using at compile-time would
be used to choose which implementation to use.

I readily admit that doing this is easier on Windows, where the number of
versions is somwhat bounded, and it's possible to get information (not
always right, of course) in one place. (Window emulators always try to match
the real thing as closely as possible, so they tend to be less incompatible
than the different versions of the real thing...)

                      Randy.