>From: "David Abrahams" <[EMAIL PROTECTED]> > Aleksey and I are trying to think of a simple metaprogramming > problem which we could use as a sort of "Hello World" example for > the MPL. This seems to be a rather hard problem. Aside from being > short, a C++ "hello, world" introduces only two library components, > cout and endl (three if you count operator<<), the problem it > solves, "printing something", is most programmers will want to do, > and it gives a small rush of excitement when you see it work. > > However, it's hard to "see a metaprogram work" except by > error/warning, and it's hard to demonstrate much of any practical > use with a very small number of library components. Some of the > simplest jobs involve numerical computation at compile-time, but I > don't really want to show that right off the bat because: > > a) of the syntactic/mental overhead of using the type wrappers > > b) The eye is easily confused by code which mixes placeholders (e.g. > "_1") in expressions with numeric constants (e.g. "2"). > > Thoughts?
How about implementing one of the "classic" metaprograms, such as factorial, or prime number finding (in credit to Erwin Unruh, who had a compile-time prime number program as one of the first ever metaprograms in C++. :) ), using MPL idioms? The results don't necessarily have to be printed out at compile-time (Erwin Unruh printed the results using compiler-warnings, but that is of course highly implementation dependent). "Hello, world" in compile-time programming doesn't necessarily have to be the same kind of program as in run-time programming, since the way it works is different. Regards, Terje _______________________________________________ Unsubscribe & other changes: http://lists.boost.org/mailman/listinfo.cgi/boost
