Re: [boost] [foreach] BOOST_AUTO_FOREACH

From: Matias Capeletto (matias.capeletto_at_[hidden])
Date: 2007-06-09 14:32:28

On 6/9/07, Eric Niebler <eric_at_[hidden]> wrote:
> Matias Capeletto wrote:
> > Hi all,
> >
> > I want to combine BOOST_FOREACH and BOOST_AUTO in my code.
> > With the current libs can do something like:
> >
> > BOOST_FOREACH( BOOST_TYPEOF( *c.begin() ) v, c )
> > {
> >     ...
> > }
> >
> > I was wondering if this kind of use can be promote to a more
> > user friendly syntax like:
> >
> > BOOST_AUTO_FOREACH( v, c )
> > {
> >      ...
> > }
>
> Or ...
>
>   #define BOOST_AUTO_FOREACH( x, y )\
>      BOOST_FOREACH( BOOST_TYPEOF( *boost::begin(y) ) x, y )
>
> There are some problems with this. There is no way to specify that you
> want to iterate by reference instead of by value. Also, if y has a
> dependent type, we'd need to use BOOST_TYPEOF_TPL instead, giving rise
> to the blasphemous BOOST_AUTO_FOREACH_TPL. Yuk. Finally, I do NOT want
> to create a dependency between foreach.hpp and typeof.hpp.
>
> Considering the problems, I'm inclined to leave it out. You're certainly
> free to define your own.

Ok, I understand the problems.

Thanks!
King regards
Matias