Struct bevy::ecs::change_detection::Mut

pub struct Mut<'w, T>
where
    T: ?Sized,
{ /* private fields */ }

Unique mutable borrow of an entity’s component or of a resource.

Implementations

impl<'w, T> Mut<'w, T>

where T: ?Sized,

pub fn new( value: &'w mut T, added: &'w mut Tick, last_changed: &'w mut Tick, last_run: Tick, this_run: Tick ) -> Mut<'w, T>

Creates a new change-detection enabled smart pointer. In almost all cases you do not need to call this method manually, as instances of Mut will be created by engine-internal code.

Many use-cases of this method would be better served by Mut::map_unchanged or Mut::reborrow.

• value - The value wrapped by this smart pointer.
• added - A Tick that stores the tick when the wrapped value was created.
• last_changed - A Tick that stores the last time the wrapped value was changed. This will be updated to the value of change_tick if the returned smart pointer is modified.
• last_run - A Tick, occurring before this_run, which is used as a reference to determine whether the wrapped value is newly added or changed.
• this_run - A Tick corresponding to the current point in time – “now”.

impl<'w, T> Mut<'w, T>

where T: ?Sized,

pub fn into_inner(self) -> &'w mut T

Consume self and return a mutable reference to the contained value while marking self as “changed”.

pub fn reborrow(&mut self) -> Mut<'_, T>

Returns a Mut<> with a smaller lifetime. This is useful if you have &mut Mut <T>, but you need a Mut<T>.

pub fn map_unchanged<U>(self, f: impl FnOnce(&mut T) -> &mut U) -> Mut<'w, U>

where U: ?Sized,

Maps to an inner value by applying a function to the contained reference, without flagging a change.

You should never modify the argument passed to the closure – if you want to modify the data without flagging a change, consider using DetectChangesMut::bypass_change_detection to make your intent explicit.

// When run, zeroes the translation of every entity.
fn reset_positions(mut transforms: Query<&mut Transform>) {
    for transform in &mut transforms {
        // We pinky promise not to modify `t` within the closure.
        // Breaking this promise will result in logic errors, but will never cause undefined behavior.
        let mut translation = transform.map_unchanged(|t| &mut t.translation);
        // Only reset the translation if it isn't already zero;
        translation.set_if_neq(Vec2::ZERO);
    }
}

pub fn as_deref_mut(&mut self) -> Mut<'_, <T as Deref>::Target>

where T: DerefMut,

Allows you access to the dereferenced value of this pointer without immediately triggering change detection.

Trait Implementations

impl<'w, T> AsMut<T> for Mut<'w, T>

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

Converts this type into a mutable reference of the (usually inferred) input type.

impl<'w, T> AsRef<T> for Mut<'w, T>

fn as_ref(&self) -> &T

Converts this type into a shared reference of the (usually inferred) input type.

impl<'w, T> Debug for Mut<'w, T>

where T: Debug + ?Sized,

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

Formats the value using the given formatter.

impl<'w, T> Deref for Mut<'w, T>

where T: ?Sized,

type Target = T

The resulting type after dereferencing.

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

Dereferences the value.

impl<'w, T> DerefMut for Mut<'w, T>

where T: ?Sized,

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

Mutably dereferences the value.

impl<'w, T> DetectChanges for Mut<'w, T>

where T: ?Sized,

fn is_added(&self) -> bool

Returns true if this value was added after the system last ran.

fn is_changed(&self) -> bool

Returns true if this value was added or mutably dereferenced either since the last time the system ran or, if the system never ran, since the beginning of the program.

fn last_changed(&self) -> Tick

Returns the change tick recording the time this data was most recently changed.

impl<'w, T> DetectChangesMut for Mut<'w, T>

where T: ?Sized,

type Inner = T

The type contained within this smart pointer

fn set_changed(&mut self)

Flags this value as having been changed.

fn set_last_changed(&mut self, last_changed: Tick)

Manually sets the change tick recording the time when this data was last mutated.

fn bypass_change_detection( &mut self ) -> &mut <Mut<'w, T> as DetectChangesMut>::Inner

Manually bypasses change detection, allowing you to mutate the underlying value without updating the change tick.

impl<'w, T> From<Mut<'w, T>> for Ref<'w, T>

where T: ?Sized,

fn from(mut_ref: Mut<'w, T>) -> Ref<'w, T>

Converts to this type from the input type.

impl<'w, T> From<NonSendMut<'w, T>> for Mut<'w, T>

where T: 'static,

fn from(other: NonSendMut<'w, T>) -> Mut<'w, T>

Convert this NonSendMut into a Mut. This allows keeping the change-detection feature of Mut while losing the specificity of NonSendMut.

impl<'w, T> From<ResMut<'w, T>> for Mut<'w, T>

where T: Resource,

fn from(other: ResMut<'w, T>) -> Mut<'w, T>

Convert this ResMut into a Mut. This allows keeping the change-detection feature of Mut while losing the specificity of ResMut for resources.

impl<'w, 'a, T> IntoIterator for &'a Mut<'w, T>

where &'a T: IntoIterator,

type Item = <&'a T as IntoIterator>::Item

The type of the elements being iterated over.

type IntoIter = <&'a T as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> <&'a Mut<'w, T> as IntoIterator>::IntoIter

Creates an iterator from a value.

impl<'w, 'a, T> IntoIterator for &'a mut Mut<'w, T>

where &'a mut T: IntoIterator,

type Item = <&'a mut T as IntoIterator>::Item

The type of the elements being iterated over.

type IntoIter = <&'a mut T as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> <&'a mut Mut<'w, T> as IntoIterator>::IntoIter

Creates an iterator from a value.