Kenny Riddile wrote:
I'm trying to create a type trait to detect the presence of a constructor with a very specific signature. Types passed to this trait will *always* have a constructor of the form:
T( const std::string& );
but some of them will have this constructor as well:
T( const std::string&, Foo& ); // Second parameter will always be a Foo&
I would like to create a type trait that returns true when the second constructor is present. I can't simply do:
!is_convertible<std::string, T>::value
since that will return false when the second constructor is present since all Ts are convertible from std::string. Is it possible to create such a trait?
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Well, I found a compromise that I'm happy with. Since the vast majority of these types will not have the "extra" constructor, I mandated that types that do have it derive from a specific type. Then I can simply use boost::is_base_of to detect them. At least this solution is only intrusive to types that already desire special treatment. Thanks for the help guys...looks like I'll have to wait for widespread std::is_constructible support before revisiting this.