Re: [Boost-users] Reference information for mpl::for_each ?

From: Vyacheslav Kononenko (groups_at_[hidden])
Date: 2005-06-14 15:51:53

--- Stephen Gross <mrstephengross_at_[hidden]> wrote:

> (1) Where can I find reference information for
> mpl::for_each (I've looked 
> around on the boost website and can't seem to find
> it).
> 
> (2) Here's what I'm trying to do: I've got an
> mpl::vector. Given some type 
> T, I want to loop across the vector and see if T is
> convertible to any of 
> the types in the vector. I tried something like
> 'for_each<typelist, 
> is_convertible<T, _1> >()' but my syntax is
> definitely wrong. Any ideas?
> 
> Thanks in advance,
> --Steve
> 
> Stephen Gross
> Case Western School of Medicine
> Cleveland, OH
> 
You can use fold in this case. So it could be
something like this:

template< typename Sequence, typename T >
struct find_convertible : fold< Sequence, void_, if_<
is_void_< _1 >, is_convertible< T, _2 >, _1 > {};

is_convertible shall return void_ in case it cannot
convert for this to work (you can use different type,
but need to change initial value and if statement
accordingly).

I made a suggestion to make such algorithm available
in the lib. But it is possible it can be simply
implemented through already existing algorithms.

Regards,
Vyacheslav