in a template argument, specify which object member to access?

[cy via Digitalmars-d-learn]

This is what I have so far. Using mixin(rawstring~templatearg) 
for every time I access the member is kind of cludgy though.

struct A {
	string up;
	string down;
	string left;
	string right;
}

template goPlaces(string D1, string D2, string D3) {
	string goPlaces(ref A a) {
		mixin("a."~D2) = "deetoo";
		return "go " ~
			mixin("a."~D1) ~ " then go " ~
			mixin("a."~D2) ~ " then go " ~
			mixin("a."~D3);		
	}
}

void main() {
	import std.stdio;
	A a = {"north","south","east","west"};
	writeln(goPlaces!("up","left","down")(a));
	writeln(a.left);
}

>top postinglol
On Monday, 8 February 2016 at 21:09:47 UTC, cy wrote:
> object.member lets me access the member of the object, but what 
> if I want to access those members in a generic way, but in a 
> different arrangement depending on context? Like if I wanted to 
> first follow a tree down, and second priority would be going 
> left to right, but then I wanted to first go right, and second 
> priority would be going down to up.
>
> struct A {
> 	string up;
> 	string down;
> 	string left;
> 	string right;
> }
>
> template goPlaces(D1,D2,D3) {
> 	string go(A a) {
> 		return "go " ~ a.D1 ~ " then go " ~ a.D2 ~ " then go " ~ a.D3;
> 	}
> }
>
> import std.stdio;
>
> void main() {
> 	A a = {"north","south","east","west"};
> 	writeln(goPlaces!(up,down,left)(a));
> }
>
> Do I just have to use a mixin? Or implement those members as 
> indexes in an array, if I want to use them differently?
>
> enum Way { UP, DOWN, LEFT, RIGHT };
> struct A {
> 	string[Way.max+1] ways;
> }
> ...