Clearly, streams can't be copied. It should be possible to move streams. According to 27.9.1.11 [ofstream.cons] paragraph 4 it is possible to move construct an std::ofstream (the same is true for std::ifstream, std::fstream, and the std::*stringstream variants). For example:
#include <iostream>
#include <fstream>
#include <string>
std::ofstream makeStream(std::string const& name) {
return std::ofstream(name);
}
int main()
{
std::ofstream out{ makeStream("example.log") };
}
Trying to move an std::ostream, e.g., to have a factory function creating an std::ofstream, an std::ostringstream, or some other stream according to a URN passed as argument doesn't work. std::ostream (well, the class template std::basic_ostream really) has a protected move constructor according to 27.7.3.1 [ostream].
Why can't std::ostream be moved itself?