[Boost-users] Re: Any constructor evaluation in compile time?

"Yutaka Leon Suematsu" writes:

Hi everyone,

I am new at the excellent Boost library. It is an incredible source of smart techniques and ticks.

I would like to ask if there is a way to evaluate, in compile time, the existence of a specific constructor, except from the constructor default and copy constructor (I know the functions has_trivial_constructor and has_trivial_copy from the type_traits library). For example in the following code, I would like to evaluate the existence of both "A(const Config& config)"

You can do something like this with is_convertible

and " template <class Random> A(const Config& config, Random& random) " constructors.

This one there's no known technique for.

Class A { A(){.} A(const Config& config){.} template <class Random> A(const Config& config, Random random){.} . }

Also, I would like to know why and how the has_trivial_constructor works.

When it works, it relies on implementation-specific magic help from the compiler. -- Dave Abrahams Boost Consulting www.boost-consulting.com