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From "Rana Dasgupta" <rdasg...@gmail.com>
Subject Re: [general] platform support
Date Wed, 09 Aug 2006 16:14:11 GMT
On 8/9/06, Tim Ellison <t.p.ellison@gmail.com> wrote:
> >Yes, it is the question you also pose elsewhere -- can we have a binary
> t>hat either (a) uses the lowest common denominator of the different
> >windows platforms API without incurring an undue penalty performance, or
> >(b) performs runtime checks and picks the best available APIs.
> There are distinct approaches as I understand it.

One option is a single binary image that contains code that supports
> multiple platforms seperately by doing a dynamic check for platform. Though
> less pernicious than a least common denominator approach,  these runtime
> checks are not healthy for a binary image that targets performance. So if
> our ideal platform were XinXP, we would incur a penalty repeatedly when
> running with it to accomodate the fact that this binary could have also run
> on W2k.

  The second option is to use a least common denominator approach where we
use code/functionality that is only available on the least platform. This is
not a good idea for obvious reasons. For example it is not a good idea not
to use the excellent vectored exception handling on WinXP and Win2003( which
intentionally sharethe same debug and kernel codebases )If this were not, we
would be writing code for DOS only.

  The third is to have a single codebase with the right _WIN32_WINNT guards
to distinguish platform specific code, and build seperate distributions for
seperate platforms. This is the most performance friendly. It has a building
cost, but the major overhead is not building, but testing. If we were to
support a platform, we would need to test on it anyway.


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