Another Properties Proposal

[Chad J]

Chad J wrote:
> 
> // baz is just some function. This is on the user's side of the prop.
> T baz(T)(Bar arg)
> {
>   auto ptr = &arg.foo; // foo is a property, a data field works too
>   T val = *ptr; // calls foo.setFoo(typeof(foo).init);
>   return val;
> }

I just realized that such a thing doesn't work at all, because nothing 
would expand to the "typeof(foo).init" that is passed to the setter.
So the idea of returning a delegate from an address-of-property probably 
isn't useful at all in this context.

The notion of having the thing returned from address-of-property be 
something that templates could work with as if it were a data field, at 
least syntactically, still might have some potential though.  Even 
better if it doesn't rely on implicit properties.

In an adjacent post, Chris Nicholson-Sauls suggested that properties 
could be "treated internally by D as just a struct which calls the 
self-named function".  Perhaps if such a struct was revealed as some 
kind of special internal library built in struct then it could be 
returned as a property's address by default.