"David Abrahams" <dave@boost-consulting.com> wrote in message news:uacpk414w.fsf@boost-consulting.com... | "Thorsten Ottosen" <nesotto@cs.auc.dk> writes: | | > "Arkadiy Vertleyb" <vertleyb@hotmail.com> wrote in message | > | Well, then I hate to say this, but IMHO this is a problem in the Boost.Range | > | design :-( | > | > It is deliberate design. | | It might still be a design mistake. well, yes, it could be. | > All generic code that uses boost.range should use unqualified calls | > to enable ADL. | > | > <aside> | > It is possible to imagine alternative designs where | > all calls to end(c) can be made qualified and still enable | > ADL; however, it requires the unqulified call of another function | > inside boost::end(c) , say adl_end(c), to enable ADL of that function. | > </aside> | | ADL might not be the best customization solution. Problems with ADL | are well-known, and there are other mechanisms; in this case static | member functions of a class template specialization might have been | better... especially since you can't stick overloads in std. For | example: | | namespace boost { namespace ranges { | | template <class Range> | struct traits; | | template <class Range> | typename traits<Range>::iterator begin(Range& r) | { | return traits<Range>::begin(r); | }; | | // ... etc... | }} | | | | > | I am not really that familiar with this library, but I assume it has to do | > | with containers, correct? Assume the following usage (pseudocode) | > | | > | Range(std::vector<MyNamespace::SomeTemplate<boost::multi-index<boost::mpl::v | > | ector> > > ) | > | | > | Now ADL will use std, boost, MyNamespace, boost::multi_index, and boost::mpl | > | to find Range. There is absolutely no guarantee that it won't find | > | conflicting functions :-( | > | > I don't get this. Surely one of the functions would be a better match than | > the others and hence called. | | The problem is that controlling which is the best match is sometimes | very difficult. Sometimes the best match doesn't get called. then how can it be the best match then? | Sometimes there is ambiguity. ADL is a very blunt instrument. If the implementation was to use a class template, what would be preffered naming? Would you want one big fat class with all the functions? Or would you like a class for each function, say for end(), std::end_impl<T>? -Thorsten