@property

[Jacob Carlborg]

On 2012-08-04 21:25, Adam D. Ruppe wrote:

> Yes, I agree in general, but if a getter returns a ref, you should
> be able to write to it... I think anyway, but it is an lvalue anyway.

Or we could disallow getters returning by reference.

> What I just added to my hacked compiler is this:
>
> =====
>   else if(e1->op == TOKcall) {
>              // for property work, if there is a setter, we should
> revert to the older style
>              // handling. If not, we can keep it as a CallExp
>              CallExp* ce = (CallExp*) e1;
>              Expression* temp_e1 = ce->e1;
>              if((temp_e1->op == TOKvar &&
> temp_e1->type->toBasetype()->ty == Tfunction)) {
>                  // this is potentially a setter.... but not necessarily
>                  fd = ((VarExp *)temp_e1)->var->isFuncDeclaration();
>                  ethis = NULL;
>                  assert(fd);
>                  FuncDeclaration *f = fd;
>                  Expressions a;
>                  a.push(e2);
>
>                  fd = f->overloadResolve(loc, ethis, &a, 1);
>                  if (fd && fd->type) {
>                      e1 = temp_e1;
>                      goto Lsetter;
>                  }
>              }
> =====
>
>
> To line 10320 - right above where the old style setter code is. It isn't
> perfect yet because it doesn't ensure we are dealing with a @property,
> but it is closer.
>
>
>
> The idea is: if we have a setter function, we should try to use it, just
> like dmd does today. If not, we'll leave the call there and see what
> happens. (If it returns ref, it will work, otherwise, it errors saying
> the property is not an lvalue.)
>
>
> So far this is passing my simple test for assignment, but not yet the op
> assigns.
>
> int a;
> @property int funcprop() {
>          return a;
> }
>
> // setter
> @property int funcprop(int s) {
>          return a = s + 10;
> }
>
> funcprop = 10; // works, funcprop == 20 now

Doesn't this already work?

> True. I think all the other uses should just work though.

Yes. Have a look at this for a workaround:

http://forum.dlang.org/thread/gknbobkfhmfszshqenng@forum.dlang.org#post-jvjs5j:248ov:241:40digitalmars.com

-- 
/Jacob Carlborg