[Boost-users] Re: Looking for more advancedtype_traits-likefunctionality

Hi, and what about member typedef's? Is it also that hopeless? Thx, Gus "Ben Hutchings" wrote in message news:A7F746377BDB7D4EA8E6623AF92F43C8163515@copper.bwsint.com...

Agoston Bejo :

...

Hi, I have took a look at some parts of the boost library, but I couldn't find what I want, and that is something like this: How can I determine if a type T has such and such member? It would look like something like this:

has_member::result (true if T::paint() exists) has_member::result (true if T::m_size exists)

The closest to this I could find is boost::type_traits but that does not provide this functionality.

Unfortunately that is impossible because templates can only manipulate constants, types and templates, not names. There is a technique that can be used to detect the definition of most operators, but it requires a separate template for each operator and it depends on being able to overload the operators through non-member functions. There may be a way to detect member functions but it cannot be done generically.