On 11/23/2011 03:21 AM, Joel de Guzman wrote:
Local cannot be an approximation of lambda. As mentioned again and again, a good approximation of lambda is already existing in Boost. Namely: bind, lambda and phoenix. I posted a Spirit example of lambda in action using Phoenix:
DSELs for lambdas have a lot of limitations (cannot use functions and member functions as-is, they must be adapted), compile-time overhead, runtime overhead (all those small functions do inhibit certain optimizations that would happen more easily with short straightforward code, instead it relies on premature aggressive inlining) and have non-obvious interactions with the rest of the code that make them hard to use for people without advanced C++ expertise, and deal to error messages that simply overwhelming and often *cannot* be understood by average coders. Now however, they're very cool, but it's just not the best solution to the problem. It's one solution, with its own set of advantages (short concise syntax, polymorphism, compile-time AST that can be manipulated and transformed) and drawbacks (see above). Boost.Local is another solution for C++03, which is however made obsolete by C++11 lambdas. Both deserve to exist, just like there is both boost::for_each and BOOST_FOREACH (the latter being obsoleted by the C++11 range for-loop) even if it's a bit late for Boost.Local to shine.