Vesa Karvonen writes:
Hi,
I have made some optimizations (resulting in an order of magnitude (10x) improvement in compile-time in some cases on GNU g++) to the library and implemented a couple of new metafunctions. The latest snapshot can now be downloaded from the Files Section (both zip and tar.bz for your convenience):
http://groups.yahoo.com/group/boost/files/LazyMPL/
Please note that the library is only a proof-of-concept made in about 2 days. It should be quite possible to provide a more comprehensive library of lazy metafunctions and provide facilities like the lambda-facility of Boost MPL. (Also, you shouldn't worry about the upper case naming used in the library.)
Lazy template metaprogramming, as shown by the lazy metaprogramming library, eliminates the number one stumbling block of template metaprogramming as described by every introduction or guide to template metaprogramming (e.g. http://www.boost.org/libs/mpl/doc/#applyif and Generative Programming section 10.11.1.3 Taking Advantage of Lazy Behavior (particularly pages 441-443... "You should remember this when writing static code" ;)).
In lazy template metaprogramming, invocations (::type) are only needed when a value needs to be explicitly examined (e.g. to extract the head of a list). Use of the typename-keyword can be practically eliminated and forwarding (use of inheritance) is the usual way to implement functions.
Vesa, I, for one, am by no means ignoring this. I'll be sure to take a closer look at your work as soon as we get the release out of the door. -- Aleksey Gurtovoy MetaCommunications Engineering