Template Question

[Mike Parker]

I've not worked much with templates in any language beyond the basics. 
Right now, I've got a problem that I've solved, but for which I'm 
looking a different solution.

What I have is a templated interface like so:

interface Foo(T)
{
     void init(T);
     void term();
     void blah();
     void bleh();
}

Then I have a Templated manager class intended to work with differently 
parameterized Foos:

class Manager(U)
{
     ...
}

The issue is that I want to make sure that Manager is instantiated with 
Foos without it knowing what the T in Foo is. This obviously doesn't work:

class Manager(U : Foo)
{
}

One way to solve the problem is to de-templatize Foo and create a new 
interface like so:

interface FooInit
{
}

interface Foo
{
    void init(FooInit fi);
}

I don't like that too much, though, since the parameters will always be 
PODs, so I'd prefer to use structs and not classes for them. The 
solution I've come up with, based on my limited knowledge, is to check 
that the parameter U for the manager implements all of the functions 
required by the Foo interface:

class Manager(U)
{
     static this()
     {
         static if(!is(typeof(&U.init)) && !is(typeof(&U.term))
                   && !is(typeof(&U.blah)) & !is(typeof(&U.bleh)));
     }
}

This works fine for my purposes, even though it allows any type that 
implements these methods, regardless of whether or not it implements Foo.

I'm curious if there is another way to do this, particularly some way to 
make sure that Manager only accepts Foo implementations without knowing 
how they are parameterized.