Re: [boost] [review] Fusion review, finalization

From: Joel de Guzman (joel_at_[hidden])
Date: 2006-05-12 01:58:29

Tobias Schwinger wrote:

> 2. Fusion and MPL placeholder expressions
>  
>    MPL placeholder expressions are very convenient for specifying the result
>    because of their lazy nature (see lines 267, 312). Of course, this approach
>    trades compile time for syntactic sugar. The syntactic sugar might not be 
>    entirely irrelevant, because it allows us to emphasize even complex problems 
>    with little code. 

Sure.

>    So, I still wonder, whether it is a good idea to use MPL lambda for the
>    result computation or not. Is it?

I think so, yes.

>    If so (even occasionanlly), it would be necessary to have at least accessors 
>    for pair members (they are needed to keep the evaluation lazy, see line 211) 
>    or, ideally, if there would be a normalization between the STL and the MPL 
>    pair concepts (then MPL's accessors, 'first' and 'second', could be borrowed).

If my suggestion to make mpl/fusion pair fully conforming mpl/fusion
sequences is accepted, then you can use code like mpl::begin<_> or
mpl::at<_, N>.

>    (It would also be cool if one could just typedef the lambda expression to nested 
>    result or inherit from a wrapper. I don't know whether it's possible and a good 
>    idea - this part is just loud thinking)...

Hmmm... can you elaborate. I lost you here.

Regards,
-- 
Joel de Guzman
http://www.boost-consulting.com
http://spirit.sf.net