Eric Niebler wrote:
Hartmut Kaiser wrote:
dan marsden wrote:
I don't think we've got anything that supports this directly at the moment.
As long as we're talking about Fusion/functional - no we haven't.
Is the sort of thing you are looking for?
fused_ctor<T> fc; T t = fc(sequence);
Where fused_ctor::operator()(Seq const&) breaks up the sequence into args for the T ctor.
Yes, that's the thing.
OK, but why duplicate the unpacking of the Sequence? All it takes is yet another adapter encapsulating a type's ctor(s) in a function object to just use fusion::(invoke|fused)_function_object. E.g: // untested code for illustration only template<typename T> struct ctor { typedef T result_type; // [...] tricky nullary case with default ctor detection // omitted for simplicity template<typename T0> T operator(T0 & a0) const { return T(a0); } template<typename T0, typename T1> T operator(T0 & a0, T1 & a1) const { return T(a0,a1); } // [...] // Note: // Sequence elements are unpacked as lvalues, so const // qualifiers on the argument types of operator() can be // deduced }; Client code (at function scope): invoke_function_object( ctor<my_class>(), argseq ); Regards, Tobias