Re: [boost] New libraries implementing C++11 features in C++03

Subject: Re: [boost] New libraries implementing C++11 features in C++03
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2011-11-23 05:03:39

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:
>
>    http://tinyurl.com/7w2h2r9

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.