Struct arc_swap::access::AccessConvert

pub struct AccessConvert<D>(pub D);

DynAccess to Access wrapper.

In previous versions, Box<dyn DynAccess> didn’t implement Access, to use inside Map one could use this wrapper. Since then, a way was found to solve it. In most cases, this wrapper is no longer necessary.

This is left in place for two reasons:

• Backwards compatibility.
• Corner-cases not covered by the found solution. For example, trait inheritance in the form of Box<dyn SomeTrait> where SomeTrait: Access doesn’t work out of the box and still needs this wrapper.

Examples

The example is for the simple case (which is no longer needed, but may help as an inspiration).

use std::sync::Arc;

use arc_swap::ArcSwap;
use arc_swap::access::{AccessConvert, DynAccess, Map};

struct Inner {
    val: usize,
}

struct Middle {
    inner: Inner,
}

struct Outer {
    middle: Middle,
}

let outer = Arc::new(ArcSwap::from_pointee(Outer {
    middle: Middle {
        inner: Inner {
            val: 42,
        }
    }
}));

let middle: Arc<dyn DynAccess<Middle>> =
    Arc::new(Map::new(outer, |outer: &Outer| &outer.middle));
let inner: Arc<dyn DynAccess<Inner>> =
    Arc::new(Map::new(AccessConvert(middle), |middle: &Middle| &middle.inner));
let guard = inner.load();
assert_eq!(42, guard.val);

Tuple Fields

0: D

Trait Implementations

impl<T, D> Access<T> for AccessConvert<D>

where D: Deref, D::Target: DynAccess<T>,

type Guard = DynGuard<T>

A guard object containing the value and keeping it alive.

fn load(&self) -> Self::Guard

The loading method.