Skip a default parameter in D

Question

I'm going through the D language tour and when I got to Functions started wondering if there's a way to skip a default parameter when calling a function, eg.:

import std.stdio;

void greet(string greeting = "Hello", string subject = "World")
{
    writefln("%s %s", greeting, subject);
}

void main()
{
    greet();
    greet("Howdy");
    greet("Hello", "D");  // duplicating default "Hello"
    // greet(, "D");      // Error: expression expected, not ','
}

I've already looked at How to enter by-name argument to a function in D?, so I know you can't pass parameters by name, and apart from that couldn't find any mention of such a feature, so asking just to make sure I didn't miss anything and there's a clear answer somewhere on the internet.

If it's not possible to skip passing a parameter when a default is available, what's the best practice for avoiding duplicating default values?

Answer 1

You cannot skip an argument, but if you know it has a default, you can automatically supply that default:

import std.traits;

...

greet(ParameterDefaults!greet[0], "D");