RE: [boost] Re: Re: Re:Re:PlatformNeutrality-withoutreinterpret_c ast<>andifdef

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