Re: [Boost-users] [mpl] insert not inserting?

From: Eric Niebler (eric_at_[hidden])
Date: 2007-03-29 14:54:19

Markus Werle wrote:
> 
> So what we really need together with the tutorials and the documentation
> is a wiki about the design and evolution of boost.

Design rationales are good. A wiki might work, but a better place might 
be in a "Rationale" section in each Boost library's documentation.

> Then Eric Niebler could explain in depth why he needs
> "static, aggregate initialization" in proto 
> (see <http://thread.gmane.org/gmane.comp.parsers.spirit.devel/2886/focus=2890>)
> and why mpl does not fit for proto. 

Static initialization in proto is important so that when DSEL authors 
declare their global primitives like _1, there are no global 
initialization order problems.

The only problem I had using MPL with proto was compile-time performance 
problems when using MPL lambdas. In order to keep compile times down, 
I've replaced as much template meta-programming in proto as possible 
with preprocessor meta-programming. And proto is a bit of a special case 
since TMP-heavy libraries are built on top of proto, so the TMP overhead 
of proto itself should be as small as possible. MPL is a very nice 
abstraction, but it's not free. Ditto for Fusion.

And yes, I measure compile time performance and don't optimize 
prematurely. :-)

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com