Pavol Droba wrote:

...

Several functors in Boost.Algorithm do not fulfill CopyConstructable requirements, e.g.

case_conv.hpp: to_lowerF, to_upperF formatter_regex.hpp: regex_formatF

I propose to replace their reference members by either corresponding pointers or by boost::reference<>'s.

All these functors are not part of the libraries's public interface. They are not documented and they can change between different versions of the library. I strongly recommend not to use them.

If you find some of them usefull, we can consider to add something with similar functionality to the public interface.

First: I apologize for using wrong nomenclature. I meant Assignable instead of CopyConstructible (the last one is fulfilled). Although Assignable is not a base requirements on functors, this requirement is needed, if the functor is e.g. a member of an iterator. An example of is boost::transform_iterator, which is used in to_upper_copy of the file case_conv.hpp. Greetings from Bremen, Daniel