From: Glen Knowles (gknowles_at_[hidden])
Date: 2002-08-06 15:48:52
From: Beman Dawes [mailto:bdawes_at_[hidden]]
> > I'm not sure his suggested implementation was addressed. My
understanding
> > is that he was advocating separate files for the implementations of, at
> > least, the major operating system "families". This would compile only
the
> > files required for a given platform, with the hope of needing much less
> > #ifdef clutter. Not the pimpl idiom, unless you wanted to classify it as
> > a compile time pimpl. :)
> >
> You just can't win on this question. In the alpha of boost::filesystem, I
> had separate implementation files for POSIX and Windows. I got complaints
> about that. I changed to single files with #ifs, and got a complaint
about
> that.
>
> The key factors to me were that with the single file with #ifs:
>
> * It made maintenance easier and prevented divergence of semantics
between
> implementations. Note that the majority of the code was not within #ifs,
> and so appeared only in one place instead of two.
>
> * It was easier to inspect to determine if the two implementations had
the
> same semantics.
>
> * It made compilation and test easier.
>
> * Over time, and in ways I can't quite put my finger on, the single file
> with #ifs just came to feel like better software engineering. KISS I
guess.
My experience has been with systems supporting only two or three platform
families. In these situations I completely agree with you, even with not
quite being able to put my finger on it. That said, I suspect that when you
support more then two or three separate implementations its easier to do
it in separate files.
Glen