template<class T_functor, class... T_args>
struct sigc::deduce_result_type< T_functor, T_args >
Deduce the return type of a functor.
typename deduce_result_type<functor_type, list of arg_types>::type
deduces a functor's result type if functor_type
inherits from sigc::functor_base and defines result_type
or if functor_type
is actually a (member) function type. Multi-type functors are not supported.
sigc++ adaptors use typename deduce_result_type<functor_type, list of arg_types>::type
to determine the return type of their templated operator()
overloads.
Adaptors in turn define a nested template class deduce_result_type
that is used by template specializations of the global deduce_result_type template to correctly deduce the return types of the adaptor's suitable template operator()
overload.