Re: [Boost-users] How to detect the presence of a particular type of constructor?

Subject: Re: [Boost-users] How to detect the presence of a particular type of constructor?
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2009-04-25 10:31:14

AMDG

Siegfried Kettlitz wrote:
> Thanks, that is just what i was looking for. :)
>
> Apparently that's the key point for detecting the implicit conversion
> constructor:
> template< typename From >
> struct does_conversion_exist
> {
>    template< typename To > struct result_
>    {
>        static no_type BOOST_TT_DECL _m_check(...);
>        static yes_type BOOST_TT_DECL _m_check(To);
>        static From _m_from;
>        enum { value = sizeof( _m_check(_m_from) ) == sizeof(yes_type) };
>    };
> };
>
>
> Can this be extended to constructors with more than one parameter?
>   

There is no known way to detect constructors except for
the special case of implicit conversions.

> As far as i can see, it applys only to conversion constructors.
>   

Right.

In Christ,
Steven Watanabe