how to use opdot

[Morusaka]

Steven Schveighoffer Wrote:
> opDot is useful if you want to make a 'wrapper' type.  That is, you want to 
> mimic another type, but you want to slightly alter the behavior.  opDot 
> allows you to 'inherit' all the member functions and fields from the wrapped 
> type.  For example, if I wanted to create a wrapper type that added a 
> 'blahblah' integer to the type, I could do this:
> 
> struct AddBlahBlah(T)
> {
>    T _t;
>    int blahblah;
> 
>    T *opDot() { return &_t;}
> }
> 
> Now, if I declare an AddBlahBlah!(C) and class C has a member foo():
> 
> C c;
> AddBlahBlah!(C) abb = AddBlahBlah!(C)(c);
> 
> abb.foo(); // translates to abb.opDot().foo()
> abb.blahblah = 5; // sets abb.blahblah to 5, doesn't affect _t
> 
> The goal of opDot is to allow one to create types that wrap other types that 
> look almost exactly the same without much effort.  For example, the 
> std.typecons.Rebindable type allows one to create a rebindable const or 
> invariant class reference while forwarding all member accesses to the 
> underlying invariant or const instance.  This feature is used for extending 
> the type system without having to extend the language, allowing compiler 
> enforcement of specific design aspects without defining them in the 
> compiler.
> 
> Normal developers will most likely never need to define opDot.
> 
> -Steve 
> 
> 

Thank you very much Steven!

Luca