Struct MutableState 

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

A value that composition observes. Compose’s MutableState.

Cloning gives another handle to the same value. Two handles compare equal when they are the same state, which is what makes a state a stable parameter: passing the same state to a composable again does not make it run.

It is Send and Sync when the value is Send, so a worker thread can hold one and write it. The write is visible at once; the composables that read it run again on the next frame, which the write asks for.

Reading takes a lock for as long as the read lasts. Reading the same state again inside MutableState::with would wait on itself.

Implementations

impl<T: 'static> MutableState<T>

pub fn get(&self) -> T

where T: Clone,

The value, recorded as read by the scope composing now.

pub fn get_untracked(&self) -> T

where T: Clone,

The value, without recording a read. A scope that only peeks is not run again when the value changes.

pub fn with<R>(&self, read: impl FnOnce(&T) -> R) -> R

Reads the value in place, recorded as read.

pub fn set(&self, value: T)

Replaces the value. Under the default policy an equal value changes nothing.

pub fn update(&self, change: impl FnOnce(&mut T))

Changes the value in place. Always a change: there is no old value left to compare against without a copy, and a caller who wants the comparison can use set.

pub fn as_state(&self) -> MutableState<T>

This state as a read-only State.

Trait Implementations

impl<T> Clone for MutableState<T>

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for MutableState<T>

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

Formats the value using the given formatter.

impl<T> Eq for MutableState<T>

impl<T> PartialEq for MutableState<T>

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl<T: Clone + 'static> State<T> for MutableState<T>

fn value(&self) -> T

The value, recorded as read by the scope composing now.