Re: [boost] [fusion-2] compile time pair

From: Eric Niebler (eric_at_[hidden])
Date: 2005-12-02 15:11:32

Andreas Pokorny wrote:
> Hi,
> The default implementation of boost::fusion::pair<first,second> only stores 
> an instance of second. I might need a fusion::pair which does not store
> that instance either, 

If you want a map with *no* runtime data, then you should use 
mpl::map<>, not fusion::map<>. mpl::map<> uses mpl::pair<>, which has no 
runtime data. (Caveat: mpl::map is broken in more than one respect at 
the moment. Hopefully, it'll be fixed soon.)

> At first I would like to explain what I am doing right now. At
> the moment I do work on an expression template framework, similiar to
> Eric Nieblers boost::proto, which was used to build boost::xpressive. 
> 
>   I do extend that library by adding a rule system which enables the user
> to define the allowed operations of a certain domain.

Yes, proto needs this. If you're extending proto, I'd gladly accept a patch.

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