macro_rules! new_vref { (let $ident:ident : VRef<$vtable:ty> for $trait_:path = $e:expr) => { ... }; (let mut $ident:ident : VRefMut<$vtable:ty> for $trait_:path = $e:expr) => { ... }; }
Expand description
Creates a VRef
or a VRefMut
suitable for an instance that implements the trait
When possible, VRef::new
or VRefMut::new
should be preferred, as they use a static vtable.
But when using the generated XxxVTable_static!
macro that is not possible and this macro can be
used instead.
Note that the downcast
will not work with references created with this macro.
use vtable::*;
#[vtable]
struct MyVTable { /* ... */ }
struct Something { /* ... */};
impl My for Something {};
let mut s = Something { /* ... */};
// declare a my_vref variable for the said VTable
new_vref!(let my_vref : VRef<MyVTable> for My = &s);
// same but mutable
new_vref!(let mut my_vref_m : VRefMut<MyVTable> for My = &mut s);