Can't declare "template parameter which takes value of any type"

[Russell Lewis]

I'd like to propose that we need a syntax for a template parameter which 
takes "a value of any type."

Of course, you can currently write templates which take values:
BEGIN CODE
	template foo(int I) { ... whatever ... }
END CODE



You can also declare IFTI functions which take parameters of any type:
BEGIN CODE
	void bar(TYPE)(TYPE argument) { ... whatever ... }
END CODE



But sometimes, you don't want to run a function...you want to declare a 
template which takes a value, but there are multiple types that the 
value might have.  Consider this snippet from real code I'm trying to write:

BEGIN CODE
	void DoThing(char argument,   void delegate() callback)
		{ ... whatever ... }
	void DoThing(string argument, void delegate() callback)
		{ ... whatever ... }

		... maybe there are lots of DoThing functions ...
		... or maybe DoThing is an IFTI function ...

	void Chain(alias FUNC, TPL...)(void delegate() callback)
	{
		FUNC(delegate void()
		      {
		         static if(TPL.length > 0)
		            Chain!(TPL)(callback);
		         else
		            callback();
		      });
	}

	// here's where the new syntax would be *really* nice
	void Chain(char ARG, TPL...)(void delegate() callback)
	{
		DoThing(ARG,
		        delegate void()
		        {
		           static if(TPL.length > 0)
			      Chain!(TPL)(callback);
			   else
			      callback();
		        });
	}


	void main()
	{
		Chain!('c','h', SomeOtherFunc, 'a','r', VariousFuncs)
		(delegate void()
		 {
		    writefln("we got a callback!");
		 });
	}
END CODE



In the example above, if DoThing had a lot of overloads, then I would 
need to have a specialized Chain template for each type.  (If Chain was 
part of a library, and DoThing was in some other code, this might be 
really difficult.)  Worse, if DoThing was an IFTI function, I wouldn't 
be able to do this at all.

However, Chain would be trivial to write if we could declare "any sort 
of value" parameters:

BEGIN CODE THAT WON'T COMPILE
	void Chain(value ARG, TPL...) { ... see above ... }
END CODE