[boost] mpl , tuples, compile-time and run-time

From: Bernard (yahoo_at_[hidden])
Date: 2003-11-13 07:17:58

Bonjour,
I've been discovering boost::MPL and I think it's very powerful ( even 
if I could not find documentations on mpl::apply and mpl::bind :-(, 
is there any ?)

When I've been using tuples, I noticed that boost::tuples::elements<> 
takes an int, and I think it prevents me from mpl::binding this 
argument.
Is there any reason not to overload it with and mpl::int_<> argument ?

Also, I've been writing my own code similar to tuples::for_each from 
tuple_ext (from boost files section) seems and it seems to fill  an 
obvious need, will is be released ?

Now, to my main question ! ( last three do not count :-) )
I would like to compute a tuple from a tuple of tuples.
I can do the static part of computing my resulting tuple type with 
mpl. How could I fill my resulting tuple with the coresponding values 
from the processed tuple ?

It seems I should be able to conditionally instanciate fetching 
functions, but I do not really see how to do it and I'd hate to 
discover that some booster already did it much better.

(I would like to collect the N'th element (if it exists) of each tuple 
from a tuple of tuples, and have them in a resulting tuple).

Thanks for any hint.

Bernard