More Elegant Settable Methods?

[jwatson-CO-edu]

Hi,

I am trying to create a struct with a settable method that has 
access to the struct scope.
Is this the only way?
Is there a way to give access without explicitly passing `this`?

```d
import std.stdio;

struct TestStruct{
     float /*------------------*/ a;
     float /*------------------*/ b;
     float function( TestStruct ) op;

     float run(){
         return op( this );
     }
}

void main(){
     TestStruct ts = TestStruct(
         2,
         3,
         function( TestStruct s ){ return s.a + s.b; }
     );

     writeln( ts.run() );
}
```