From: Chad Fowler <chad@...>
Date: 2003-01-24T05:16:34+09:00
Subject: Re: emulating C preprocessor's #if


Rubicon does some things that might be similar to what you want (or maybe 
not).  Have a look at http://www.rubygarden.org/triple-r/index.html

Chad

On Fri, 24 Jan 2003, Berger, Daniel wrote:

> > -----Original Message-----
> > From: Joel VanderWerf [mailto:vjoel@PATH.Berkeley.EDU] 
> > 
> > My example was too simple :)
> > 
> > I'm thinking of a case where platform-dependent code is mixed with 
> > independent code and hard to factor out without making a lot of extra 
> > method calls. Also, if you have more variables than just 
> > platform, you 
> > get combinatorial explosion if you have to write a separate 
> > method for 
> > each possibility. My suggestion is a last resort...
> 
> Hi Joel,
> 
> My philosophy has been to create separate source files for each platform,
> then create a symbolic link to the correct file(s) during the installation
> phase.  You can look at sys-proctable for a good example of how I do things
> (which I adopted from Dan Urist).
> 
> This strategy offers a couple of big advantages:
> 
> 1) Avoids tons of ifdef's.  This gets especially nasty as the number of
> platforms you're going to support grows.
> 2) Makes testing easier.  If I make a change to the Linux source for
> example, I don't need to go back and retest to make sure I didn't
> accidentally break something for Solaris or FreeBSD.
> 3) Organization.  Because my code is less cluttered and consistent (for that
> platform), it's easier for me to stay focused on what needs to be done for a
> given platform.
> 
> There are some drawbacks.  If your code is very similar, you'll be doing a
> lot of copy/paste, and if you make a minor change in one platform, you have
> to remember to copy/paste it to the other platforms where the code is
> identical (at least, if you want consistent behavior between platforms, and
> I'm assuming you do).  In the cases where you have a method that you know is
> platform independent, put it in a separate module and have each platform
> independent file include it.  Then, you only need to change that method in
> *one* place.
> 
> Also, having more files may be a pain for you.  It's more CVS
> checkin/checkout for example.
> 
> I can safely say I haven't regretted separating the source one bit, but then
> I've had relatively small source files to deal with.
> 
> Regards,
> 
> Dan
>