Struct VarWriteGuard 

pub struct VarWriteGuard<'a, T>
where
    T: Send + Sync + 'static + ?Sized,
{ /* private fields */ }

A write lock guard returned by Var::write or WeakVar::write.

While the guard is alive, it holds an exclusive lock on the underlying value. When the guard is dropped, the variable is registered as having been read and, by default, written, which bumps the variable’s version and triggers dependent UI updates.

If no observable change occurred, call VarWriteGuard::cancel_change before dropping the guard to prevent the version bump.

Mapped guards produced by VarWriteGuard::map and friends preserve the same behavior: the write is committed (unless canceled) when the final mapped guard is dropped.

Implementations

impl<'a, T> VarWriteGuard<'a, T>

where T: Send + Sync + 'static + ?Sized,

pub fn cancel_change(&mut self)

Prevents the dependency tracking system from registering a change.

When this is called, the Var’s version number will not be incremented upon Drop.

pub fn map<U>( this: VarWriteGuard<'a, T>, f: impl FnOnce(&mut T) -> &mut U, ) -> VarWriteGuard<'a, U>

where U: Send + Sync + 'static + ?Sized,

Maps a write guard to a subfield, like RwLockWriteGuard::map.

This is an associated function that needs to be used as VarWriteGuard::map(...).

pub fn try_map<U>( this: VarWriteGuard<'a, T>, f: impl FnOnce(&mut T) -> Option<&mut U>, ) -> Result<VarWriteGuard<'a, U>, VarWriteGuard<'a, T>>

where U: Send + Sync + 'static + ?Sized,

Fallible map, like RwLockWriteGuard::try_map.

This is an associated function that needs to be used as VarWriteGuard::try_map(...).

pub fn try_map_or_err<U, E>( this: VarWriteGuard<'a, T>, f: impl FnOnce(&mut T) -> Result<&mut U, E>, ) -> Result<VarWriteGuard<'a, U>, (VarWriteGuard<'a, T>, E)>

where U: Send + Sync + 'static + ?Sized,

Fallible map, like RwLockWriteGuard::try_map, but returns the error produced by the mapping function.

This is an associated function that needs to be used as VarWriteGuard::try_map_or_err(...).

Trait Implementations

impl<'a, T> Deref for VarWriteGuard<'a, T>

where T: Send + Sync + 'static + ?Sized,

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &<VarWriteGuard<'a, T> as Deref>::Target

Dereferences the value.

impl<'a, T> DerefMut for VarWriteGuard<'a, T>

where T: Send + Sync + 'static + ?Sized,

fn deref_mut(&mut self) -> &mut <VarWriteGuard<'a, T> as Deref>::Target

Mutably dereferences the value.

impl<'a, T> Drop for VarWriteGuard<'a, T>

where T: Send + Sync + 'static + ?Sized,

fn drop(&mut self)

Executes the destructor for this type.

fn pin_drop(self: Pin<&mut Self>)

🔬This is a nightly-only experimental API. (pin_ergonomics)

Execute the destructor for this type, but different to Drop::drop, it requires self to be pinned.