There is an issue when passing a delegate as an class alias template parameter to be used with std.functional.binaryFun. Look at this code:

import std.stdio;
import std.functional;

class Foo(T, alias greater = "a > b")
{
	private alias compare = binaryFun!(greater);

	public this()
	{
		writefln("%s", compare(2, 1));
	}
}

void main(string[] args)
{
	// These work:
	auto foo1 = new Foo!(int, "a > b");
	auto foo2 = new Foo!(int, (a, b) => a > b);
	auto foo4 = new Foo!(int, delegate(a, b){return a > b;});

	// The following works when the delegate method is called without 'this.' 
	// otherwise they generate linker Errors:
	auto foo3 = new Foo!(int, (int a, int b) => a > b);
	auto foo5 = new Foo!(int, delegate(int a, int b){return a > b;});
}

If i remove the 'this.' from the compare method call, all works fine. After that call, i can call compare *with* 'this.' and all works. But there has to be an initial call made without the 'this.' for it to work from then on.

If i leave the 'this.' in place and pass a delegate as the compare function using types in the parameter list, a linker error occurs when calling the delegate.