typedef alternative

[Yao G.]

Hello.

Is there an alternative to typedef? I need to define three structs that  
have exactly the same methods and properties, yet represent different  
stuff.

Example:
---
struct Foo
{
    this( int f ) {
        _foo = f;
    }

    int asNumber() {
        return _foo;
    }

    private immutable int _foo;
}

// This should be typedef, but as it's going to be deprecated...
alias Foo Year;
alias Foo Month;
alias Foo Day;


void bar( Year y, Month m, Day d ) {
    // ...
}

// This should compile, obviously.
bar( Year(2010), Month(8), Day(14) );

// But this shouldn't
bar( Day(1), Year(1), Month(1) );
---

So, what options do I have? I know that typedef is scheduled to  
deprecation, so I would like to know if there's something else.


--
Yao G.