pub struct ManualEventReader<E: Event> { /* private fields */ }
Expand description

Stores the state for an EventReader.

Access to the Events<E> resource is required to read any incoming events.

In almost all cases, you should just use an EventReader, which will automatically manage the state for you.

However, this type can be useful if you need to manually track events, such as when you’re attempting to send and receive events of the same type in the same system.

Example

use bevy_ecs::prelude::*;
use bevy_ecs::event::{Event, Events, ManualEventReader};

#[derive(Event, Clone, Debug)]
struct MyEvent;

/// A system that both sends and receives events using a [`Local`] [`ManualEventReader`].
fn send_and_receive_manual_event_reader(
    // The `Local` `SystemParam` stores state inside the system itself, rather than in the world.
    // `ManualEventReader<T>` is the internal state of `EventReader<T>`, which tracks which events have been seen.
    mut local_event_reader: Local<ManualEventReader<MyEvent>>,
    // We can access the `Events` resource mutably, allowing us to both read and write its contents.
    mut events: ResMut<Events<MyEvent>>,
) {
    // We must collect the events to resend, because we can't mutate events while we're iterating over the events.
    let mut events_to_resend = Vec::new();

    for event in local_event_reader.read(&events) {
         events_to_resend.push(event.clone());
    }

    for event in events_to_resend {
        events.send(MyEvent);
    }
}

Implementations§

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impl<E: Event> ManualEventReader<E>

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pub fn read<'a>(&'a mut self, events: &'a Events<E>) -> EventIterator<'a, E>

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pub fn read_with_id<'a>( &'a mut self, events: &'a Events<E> ) -> EventIteratorWithId<'a, E>

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pub fn len(&self, events: &Events<E>) -> usize

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pub fn missed_events(&self, events: &Events<E>) -> usize

Amount of events we missed.

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pub fn is_empty(&self, events: &Events<E>) -> bool

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pub fn clear(&mut self, events: &Events<E>)

Trait Implementations§

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impl<E: Debug + Event> Debug for ManualEventReader<E>

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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<E: Event> Default for ManualEventReader<E>

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fn default() -> Self

Returns the “default value” for a type. Read more

Auto Trait Implementations§

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impl<E> RefUnwindSafe for ManualEventReader<E>
where E: RefUnwindSafe,

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impl<E> Send for ManualEventReader<E>

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impl<E> Sync for ManualEventReader<E>

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impl<E> Unpin for ManualEventReader<E>
where E: Unpin,

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impl<E> UnwindSafe for ManualEventReader<E>
where E: UnwindSafe,

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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> FromWorld for T
where T: Default,

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fn from_world(_world: &mut World) -> T

Creates Self using data from the given World.
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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