change 'this' pointer for structs to reference type

[Jason House]

Andrei Alexandrescu Wrote:

> Robert Fraser wrote:
> > Walter Bright wrote:
> >> Andrei suggested this change, and I think it is a great idea. D ought 
> >> to be moving away from pointers for routine work, and this would make 
> >> a lot of sense.
> >>
> >> It would entail some changes to user code, mostly when dealing with 
> >> the opCmp and opEquals member functions. The function signatures for 
> >> them would be changed to opCmp(ref const S).
> > 
> > While we're at it, let's have "in" return a reference instead of a 
> > pointer for AAs.
> 
> Unfortunately that won't be possible because references can't be null.

Us that true of class reference parameters to functions? I doubt it. I would love to see nullable and non-nullable types in D.