Hi All,

  Request your help, on how o find the single type of a tuple return type function, eg,

auto Fn (){
Array!string a;
Array!int b;
Array!ulong c;
return tuple(a, b, c);
}

if we use "ReturnType!Fn" it gives us the output as (Array!string,Array!int, Array!ulong) but what is need is the return type of  each of the value as
a = Array!string; b = Array!int; c = Array!ulong

void main () {
ReturnType!Fn[0] Dcol;  //similar like this line
writeln(Dcol[]);
}

From,
Vino.B

On Thursday, 4 January 2018 at 15:50:35 UTC, Vino wrote:
> Hi All,
>
>   Request your help, on how o find the single type of a tuple return type function, eg,
>
> auto Fn (){
> Array!string a;
> Array!int b;
> Array!ulong c;
> return tuple(a, b, c);
> }
>
> if we use "ReturnType!Fn" it gives us the output as (Array!string,Array!int, Array!ulong) but what is need is the return type of  each of the value as
> a = Array!string; b = Array!int; c = Array!ulong
>
> void main () {
> ReturnType!Fn[0] Dcol;  //similar like this line
> writeln(Dcol[]);
> }
>
> From,
> Vino.B

ReturnType!Fn[0] tries to give you the 0th field of the tuple, but as the error message indicates, you can't do that without an instance. What you want is the *type* of the field, as given by typeof:

    typeof(ReturnType!Fn[0]) Dcol;

This can be made a bit simpler by noticing that ReturnType is unnecessary here:

    typeof(Fn()[0]) Dcol;

However, if Fn() takes a bunch of complex parameters, this might not actually be simpler.

--
  Simen

On Thursday, 4 January 2018 at 16:09:07 UTC, Simen Kjærås wrote:
> On Thursday, 4 January 2018 at 15:50:35 UTC, Vino wrote:
>> [...]
>
> ReturnType!Fn[0] tries to give you the 0th field of the tuple, but as the error message indicates, you can't do that without an instance. What you want is the *type* of the field, as given by typeof:
>
>     typeof(ReturnType!Fn[0]) Dcol;
>
> This can be made a bit simpler by noticing that ReturnType is unnecessary here:
>
>     typeof(Fn()[0]) Dcol;
>
> However, if Fn() takes a bunch of complex parameters, this might not actually be simpler.
>
> --
>   Simen

HI Simen,

 Thank you very much, your solution was helpful.

From,
Vino.B