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

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

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impl<'w, T: ?Sized> Mut<'w, T>

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

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”.
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impl<'w, T: ?Sized> Mut<'w, T>

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

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

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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>.

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

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);
    }
}
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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.

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

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

Converts this type into a mutable reference of the (usually inferred) input type.
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impl<'w, T> AsRef<T> for Mut<'w, T>

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fn as_ref(&self) -> &T

Converts this type into a shared reference of the (usually inferred) input type.
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impl<'w, T> Debug for Mut<'w, T>
where T: Debug + ?Sized,

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

Formats the value using the given formatter. Read more
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impl<'w, T: ?Sized> Deref for Mut<'w, T>

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type Target = T

The resulting type after dereferencing.
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fn deref(&self) -> &Self::Target

Dereferences the value.
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impl<'w, T: ?Sized> DerefMut for Mut<'w, T>

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fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.
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impl<'w, T: ?Sized> DetectChanges for Mut<'w, T>

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fn is_added(&self) -> bool

Returns true if this value was added after the system last ran.
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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. Read more
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fn last_changed(&self) -> Tick

Returns the change tick recording the time this data was most recently changed. Read more
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impl<'w, T: ?Sized> DetectChangesMut for Mut<'w, T>

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type Inner = T

The type contained within this smart pointer Read more
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fn set_changed(&mut self)

Flags this value as having been changed. Read more
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fn set_last_changed(&mut self, last_changed: Tick)

Manually sets the change tick recording the time when this data was last mutated. Read more
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fn bypass_change_detection(&mut self) -> &mut Self::Inner

Manually bypasses change detection, allowing you to mutate the underlying value without updating the change tick. Read more
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impl<'w, T: ?Sized> From<Mut<'w, T>> for Ref<'w, T>

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

Converts to this type from the input type.
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impl<'w, T: 'static> From<NonSendMut<'w, T>> for Mut<'w, T>

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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.

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

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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.

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

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

The type of the elements being iterated over.
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type IntoIter = <&'a T as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?
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fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value. Read more
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impl<'w, 'a, T> IntoIterator for &'a mut Mut<'w, T>

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

The type of the elements being iterated over.
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type IntoIter = <&'a mut T as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?
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fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value. Read more

Auto Trait Implementations§

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impl<'w, T: ?Sized> RefUnwindSafe for Mut<'w, T>
where T: RefUnwindSafe,

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impl<'w, T: ?Sized> Send for Mut<'w, T>
where T: Send,

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impl<'w, T: ?Sized> Sync for Mut<'w, T>
where T: Sync,

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impl<'w, T: ?Sized> Unpin for Mut<'w, T>

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impl<'w, T> !UnwindSafe for Mut<'w, T>

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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

Mutably borrows from an owned value. Read more
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impl<T> Downcast for T
where T: Any,

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fn into_any(self: Box<T>) -> Box<dyn Any>

Convert Box<dyn Trait> (where Trait: Downcast) to Box<dyn Any>. Box<dyn Any> can then be further downcast into Box<ConcreteType> where ConcreteType implements Trait.
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fn into_any_rc(self: Rc<T>) -> Rc<dyn Any>

Convert Rc<Trait> (where Trait: Downcast) to Rc<Any>. Rc<Any> can then be further downcast into Rc<ConcreteType> where ConcreteType implements Trait.
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fn as_any(&self) -> &(dyn Any + 'static)

Convert &Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &Any’s vtable from &Trait’s.
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fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)

Convert &mut Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &mut Any’s vtable from &mut Trait’s.
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impl<T> DowncastSync for T
where T: Any + Send + Sync,

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fn into_any_arc(self: Arc<T>) -> Arc<dyn Any + Send + Sync>

Convert Arc<Trait> (where Trait: Downcast) to Arc<Any>. Arc<Any> can then be further downcast into Arc<ConcreteType> where ConcreteType implements Trait.
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more