I find this template to be really handy for use with staticMap, and I'm wondering if it exists in Phobos in some form so that I can stop rewriting it:

private template Extract(string fieldName)
{
	template Extract(T)
	{
		mixin(`alias Extract = T.`~fieldName~`;`);
	}
}

Used like so:
struct Foo(T)
{
    alias Type = T;
}

alias FooTypes = staticMap!(Extract!"Type", TypeTuple!(Foo!int, Foo!
double));

On 8/1/13, Justin Whear <justin@economicmodeling.com> wrote:
> I find this template to be really handy for use with staticMap, and I'm wondering if it exists in Phobos in some form so that I can stop rewriting it:

Try this:

import std.typetuple;

template ExtractTypes(T)
{
    static if (is(T : T!Y, Y...))
        alias ExtractTypes = Y;
    else
        static assert(0);
}

struct Foo(T)
{
}

void main()
{
    alias FooTypes = staticMap!(ExtractTypes, TypeTuple!(Foo!int, Foo!double));
    pragma(msg, FooTypes);
}