Macro topo::call

macro_rules! call {
    ($($input:tt)*) => { ... };
}

Calls the provided expression within an Env bound to the callsite, optionally passing an environment to the child scope.

let prev = topo::Id::current();
topo::call!(assert_ne!(prev, topo::Id::current()));

Adding an env! { ... } directive to the macro input will take ownership of provided values and make them available to the code run in the Point created by the invocation.

#[derive(Debug, Eq, PartialEq)]
struct Submarine(usize);

assert!(topo::Env::get::<Submarine>().is_none());

topo::call!({
    assert_eq!(&Submarine(1), &*topo::Env::get::<Submarine>().unwrap());

    topo::call!({
        assert_eq!(&Submarine(2), &*topo::Env::get::<Submarine>().unwrap());
    }, env! {
        Submarine => Submarine(2),
    });

    assert_eq!(&Submarine(1), &*topo::Env::get::<Submarine>().unwrap());
}, env! {
    Submarine => Submarine(1),
});

assert!(topo::Env::get::<Submarine>().is_none());