Passing Arguments on in Variadic Functions

[Adam D. Ruppe via Digitalmars-d-learn]

On Monday, 14 September 2015 at 19:59:18 UTC, jmh530 wrote:
> In R, it is easy to have some optional inputs labeled as ... 
> and then pass all those optional inputs in to another function. 
> I was trying to get something similar to work in a templated D 
> function, but I couldn't quite get the same behavior. What I 
> have below is what I was able to get working.

You want to generally avoid the varargs and instead use variadic 
templates. The syntax is similar but a bit different:

R test(R, E, Args...)(Args args) {
     static if(Args.length == 0)
         // no additional arguments
     else
         return sum(args);
}


or whatever you actually need. But what this does is take any 
number of arguments of various types but makes that length and 
type available at compile time for static if inspection.

The args represents the whole list and you can loop over it, 
convert to an array with `[args]` (if they are all compatible 
types, or pass to another function as a group like I did here.

This is the way writeln is implemented btw.