'strong types' a la boost

[Namespace via Digitalmars-d-learn]

You can do it this way:
----
struct dollars_t {
     uint _dollar;

     this(uint d) {
         _dollar = d;
     }

     alias _dollar this;
}

struct cents_t {
     uint _cent;

     this(uint c) {
         _cent = c;
     }

     alias _cent this;
}

void do_something_with_dollars(dollars_t d) {
     writeln(d);
}

void main() {
     dollars_t d = 1;

     do_something_with_dollars(d);

     cents_t c = 2;

     //do_something_with_dollars(c);
     //do_something_with_dollars(2);
}
----

Or you can create your own small TypeDef:

----
struct TypeDef(T, size_t l = __LINE__) {
     T _val;

     this(T v) {
         _val = v;
     }

     alias _val this;
}

alias dollars_t = TypeDef!(uint);
alias cents_t = TypeDef!(uint);
----

Thanks to the second template parameter 'l' the template 
instances of dollars_t and cents_t aren't equal.