Array to argument list

[Sergey Gromov]

Simen Haugen <simen at norstat.no> wrote:
> I have an array, but I want to send them one by one to a function that 
> has variadic arguments. Is there a way to do this at runtime?
> 
> void p(A ...)(A Args) {}
> p([1, 2, 3]); // I want this to become p(1, 2, 3) somehow...

With a bit of template trickery I've got this:

> import std.stdio;
> 
> void p(A ...)(A Args) {
>   writeln(A.stringof);
>   writeln(Args[4]);
> }
> 
> void PassArrayAsTuple(alias fun, T: E[S], E, size_t S, R...)(T arr, R rest) {
>   static if (S)
>     PassArrayAsTuple!(fun)(cast(E[S-1])arr, arr[$-1], rest);
>   else
>     fun(rest);
> }
> 
> void main() {
>   PassArrayAsTuple!(p)("array");
> }

Obviously it works only for static arrays.
I wanted to come up with something like

p(ArrayTuple!("array"));

but the trick with casting a static array to a smaller static array does 
not work for template arguments.  I'm not sure that it should work for 
function arguments either, bit it works in DMD 2.019 indeed.