Indexed foreach on struct?

[H. S. Teoh]

On Mon, Jan 23, 2012 at 03:32:07PM -0500, Matt Soucy wrote:
> So I was messing around with some code I've been writing recently,
> and I wanted to use a foreach on a struct as if it were an
> associative array. The problem is, I can't find any information on
> how to do that.
[...]
> I don't see any sort of opApply or similar to do this, and the
> foreach section of dlang.org doesn't help. Is there a way to do it,
> or do I need to do a workaround?
[...]

You can use opApply. Sample test program:

	struct Test {
		int opApply(int delegate(ref int) dg) {
			auto ret = 0;
			for (auto i=0; ret==0 && i<5; i++) {
				ret = dg(i);
			}
			return ret;
		}
	}

	import std.stdio;
	void main() {
		Test t;

		foreach (n; t) {
			writeln(n);
		}
	}

Program prints:

	0
	1
	2
	3
	4

Hope that helps.


T

-- 
If you look at a thing nine hundred and ninety-nine times, you are perfectly safe; if you look at it the thousandth time, you are in frightful danger of seeing it for the first time. -- G. K. Chesterton