Re: [boost] Boost.MathConstants: Review - is this the prototype?

From: Ed Brey (brey_at_[hidden])
Date: 2001-04-24 12:31:15

From: "Jens Maurer" <Jens.Maurer_at_[hidden]>
>
> I like the template-based interface proposed earlier better,
> because it allows e.g. interval or boost::rational<int> constants.

I agree.  It also solves the problem of getting access to constants of a
given type using reasonably short names, without having to specificly
declare each constant in use.

> > How is constant folding accomplished, given that the definition
appears
> > to be out-of-line?
>
> Allowing constant folding (or not) is a quality-of-implementation
issue
> and should not affect the interface.  (In particular, implementors
> may choose to define the constants inline, but that's not what I'd
> do for the generic boost implementation.)

I agree that it's a QOI issue.  All other things being equal, supporting
constant folding makes the library higher-quality.  Why wouldn't we want
the boost library to have this quality?  If not boost, where would one
go to find an implementation with this quality?  I presume that there is
a tradeoff involved here, but I fail to see what it is, and could use
some enlightening.  What trouble is there in putting everything in the
header, with #ifdefs sprinkled in as necessary?