Hello,
- make adaptor expressions return const rvalues. The const rvalues will bind to T& arguments (where T is a template parameter) by deducing T to be const.
- make even the const_iterators for such adaptors mutable (writable) iterators
This accurately reflects the fact that such adaptors don't own their values.
If boost::sort is supposed to be chainable (which seems a good idea), then let's not start with adaptors. We already need a solution for boost::sort( std::vector() ); If the solution is template<typename Range> boost::sort( Range && ); then in boost::sort( boost::adaptors::reverse( std::vector() ) ); reverse should probably derive mutable iterators from mutable rvalues, so would have signature: reverse( Range && ); So the policy is: All range functions and adaptors take all ranges by &&, and range::iterator<rvalue>::type is mutable, in particular for adaptors. To chain from a function, return via std::forward<Range>. Problem solved? Arno -- Dr. Arno Schödl | aschoedl@think-cell.com Technical Director think-cell Software GmbH | Chausseestr. 8/E | 10115 Berlin | Germany http://www.think-cell.com | phone +49 30 666473-10 | US phone +1 800 891 8091 Amtsgericht Berlin-Charlottenburg, HRB 85229 | European Union VAT Id DE813474306 Directors: Dr. Markus Hannebauer, Dr. Arno Schoedl