Have multiple references to a struct by trait

[HeroesGrave]

There was one feature of the @-pointer that has not been fixed since it was removed.

If you wanted to pass a struct around by referring to it as a trait, you could do @SomeTrait.

~-ptrs aren't always suitable for this because you may need more than one reference to the struct underneath the trait.

&-ptrs aren't suitable for this... well, because they aren't. :P

Obviously Rc, which is supposed to be the replacement for '@' doesn't work because you'd need another pointer inside it anyway.

Is there some way that this functionality can be restored?

[huonw]

Obviously Rc, which is supposed to be the replacement for '@' doesn't work because you'd need another pointer inside it anyway.

Rc<~Trait> is a substitute that should work for many instances of shared ownership trait-objects. (Except for the extra indirection, and some size_of details, this will behave almost exactly like Rc<Trait>.)

In any case, this is something that will hopefully come out of the "dynamically sized types" proposals (or similar; #6308) and/or the smart pointer work (probably both).

(Also, if you really need it, @ and @Trait objects still exist, you can add #[feature(managed_boxes)]; at the top of your crate file (NB. the semicolon is required)... If anyone asks, I didn't tell you this. ;) )

[HeroesGrave]

Wait, so Rc<~Trait> lets you have multiple references to an owned pointer?

Thanks for the help.