Re: [boost] [review] pqs

From: David Greene (greened_at_[hidden])
Date: 2006-06-07 15:12:35

David Abrahams wrote:
> "David A. Greene" <greened_at_[hidden]> writes:

>>It is also, IMHO, one of the best practical examples of template
>>metaprogramming.
> 
> I just want to clear something up about this.  It's not directed at
> PQS in particular, but at the whole domain of dimensional analysis as
> an example of TMP.
> 
> Dimensional analysis is really a very poor example of what TMP can do:
> interesting TMP involves some generation of code that actually "does
> something," as in the state machine example in C++TMP or Blitz++
> expression templates or Boost.Lambda.  Dimensional analysis basically
> only adds error messages where they wouldn't otherwise have been.

Not to nitpick, but I didn't say "interesting," I said "practical
example."  Catching these kinds of errors at compile-time is immensely
practical.  Not that lambda, etc. are not, but dimensional analysis is
something that most programmers can grasp immediately, amking it a
very good example of the usefulness of TMP.

Essentially, TMP is being used to extend the type system.  When I
talk to, say, Java users about TMP, this is something they can grasp.

                     -Dave