Macro cglue::as_ref

as_ref!() { /* proc-macro */ }

Checked cast to a list of optional traits.

The syntax is similar to a cast expression, but uses impl keyword:

as_ref!(obj impl Trait1 + Trait2 + Trait3);

as_ref! is non-final, meaning once the reference is dropped, the original group object can be used mutably.

This macro accepts either:

1. A list of optional traits, without any mandatory traits.

or

2. A list of optional traits, with every mandatory trait.

In either case a successfully cast object will still implement the mandatory traits.