Re: [Boost-users] [Enable-if] Selectively instantiating methods.

On Fri, 23 Sep 2011 00:51:40 -0700, Robert Jones wrote:

Hi All

This doesn't work.

template<typename T> struct S { typename disable_if::type mutating_method(); };

I understand why not, although only after the compiler threw it out, but obviously (in hindsight), the method itself is not a template, so can't be selectively instantiated.

The question is whether and how I can achieve the effect I'm after, ie., that the method is not present if the struct is instantiated with a const type?

Thx, Rob.

See http://thread.gmane.org/gmane.comp.lib.boost.devel/222181/focus=222402 Short answer (from the cited post):

...

template <class U> struct T { void f() { f_impl((0)); }

private: template <class T> typename enable_if< mpl::and_< is_convertible, some_condition_on<U>

...

::type f_impl(T) { .... } };

Basically introduce a dummy parameter with a dummy template type that's not used in f_impl. Mostafa