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Thorsten Ottosen wrote:

BOOST_ITER_FOREACH( i, get_range() ) { std::cout << *i; }

Eric Niebler wrote:

It's not implementable in standard C++, unless you know something I don't.

Hello Eric, can you provide some hints why this is not possible? For example, can't we use some (boost::?)typeof logic to fetch the iterators type? ;-) David.

"Eric Niebler" <eric@boost-consulting.com> wrote

Even if you were willing to accept that, in order to use this macro, you may have to register types with BOOST_TYPEOF (an interface I'm not overly fond of), there are still problems. Registering types for iterators is notoriously difficult. How would you write the BOOST_TYPEOF registrations for the std::vector iterators, for instance, considering that they could very well be defined as:

namespace std { template<class T, class Al> struct vector { struct iterator { //... }; }; }

// register std::vector<T,Al>::iterator BOOST_TYPEOF_REGISTER_TYPE(?????)

Has anyone solved this problem?

No. But you can write something like following: for (BOOST_TYPEOF(v)::iterator it = v.begin(); ... Of course, this introduces another issue -- the need to choose between "iterator" and "const_iterator" based on the constness of the vector. But this should be possible to do... The registration problem is still there... One thing that could be done (and was discussed before in relation to result_of) is to enable compile-time detection of whether typeof is possible for a given expression (meaning native typeof is used or all needed types are registered) without causing compiler error. In theory then, you could use it to optimize your FOREACH provided typeof is available. Regards, Arkadiy Regards, Arkadiy