Trait AddSingleObserver 

pub trait AddSingleObserver {
    // Required methods
    fn has_single_observer<E>(&self) -> bool
       where E: SingleEvent;
    fn add_single_observer<E, B, M>(
        self,
        observer: impl IntoSingleObserverSystem<E, B, M>,
    ) -> Self
       where E: SingleEvent,
             B: Bundle;
}

Trait used to register single observers for SingleEvents.

Required Methods

fn has_single_observer<E>(&self) -> bool

where E: SingleEvent,

Checks if an observer is registered for a given SingleEvent.

fn add_single_observer<E, B, M>( self, observer: impl IntoSingleObserverSystem<E, B, M>, ) -> Self

where E: SingleEvent, B: Bundle,

Adds a single observer for a given SingleEvent and guarantees that it’s the only one registered.

Panic

This will panic if an observer for the same event is already registered.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementations on Foreign Types

impl AddSingleObserver for &mut App

fn has_single_observer<E>(&self) -> bool

where E: SingleEvent,

fn add_single_observer<E, B, M>( self, observer: impl IntoSingleObserverSystem<E, B, M>, ) -> &mut App

where E: SingleEvent, B: Bundle,

Implementors