Struct VisitingMut

pub struct VisitingMut<T> { /* private fields */ }

Container that automatically returns ownership of a value to another async context upon exiting scope, allowing mutable access to the value while active.

VisitingMut implements both Deref and DerefMut to allow for immutable or mutable access to the wrapped value, either explicitly using the unary * operator or implicitly by the compiler under various circumstances. More information can be found in the Deref trait and DerefMut trait documentation.

VisitingMut instances can be permanently downgraded to VisitingRef using either VisitingMut::downgrade or the From trait implementation for VisitingRef. A VisitingRef cannot be converted back into a VisitingMut.

Implementations

impl<T> VisitingMut<T>

pub fn new(value: T) -> (Self, Return<T>)

Creates a new VisitingMut wrapping the given value, along with a future that resolves back the wrapped value once the VisitingMut is dropped.

Examples

use visiting_ref::VisitingMut;

let (mut item, receiver) = VisitingMut::new(5);
assert_eq!(*item, 5);

*item = 7;

drop(item);
let original = receiver.await;
assert_eq!(original, 7);

pub fn downgrade(value: Self) -> VisitingRef<T>

Permanently downgrades a VisitingMut into a VisitingRef.

Examples

use visiting_ref::VisitingMut;

let (mut item, receiver) = VisitingMut::new(5);
assert_eq!(*item, 5);

*item = 7;

let item = VisitingMut::downgrade(item);
assert_eq!(*item, 7);

pub fn run_with<U, R>( value: T, f: impl FnOnce(VisitingMut<T>) -> R, ) -> impl Future<Output = (T, U)>

where R: Future<Output = U>,

Wraps a given T value in a VisitingMut and runs an asynchronous closure with the VisitingMut<T> as its argument.

Examples

use visiting_ref::VisitingMut;

struct Foo {
    value: i32,
}

let foo = Foo { value: 27 };

let (foo, result) = VisitingMut::run_with(foo, |mut foo| {
    async move {
        foo.value *= 3;
        foo.value
    }
})
.await;

assert_eq!(result, 81);
assert_eq!(foo.value, 81);

Trait Implementations

impl<T> Binary for VisitingMut<T>

where T: Binary,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Debug for VisitingMut<T>

where T: Debug,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Deref for VisitingMut<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &T

Dereferences the value.

impl<T> DerefMut for VisitingMut<T>

fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.

impl<T> Display for VisitingMut<T>

where T: Display,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> From<VisitingMut<T>> for VisitingRef<T>

fn from(value: VisitingMut<T>) -> Self

Converts to this type from the input type.

impl<T> LowerExp for VisitingMut<T>

where T: LowerExp,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> LowerHex for VisitingMut<T>

where T: LowerHex,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Octal for VisitingMut<T>

where T: Octal,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Pointer for VisitingMut<T>

where T: Pointer,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> UpperExp for VisitingMut<T>

where T: UpperExp,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> UpperHex for VisitingMut<T>

where T: UpperHex,

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.