Struct Fallbacks 

pub struct Fallbacks { /* private fields */ }

The Fallback behavior is used to try different strategies until one succeeds.

It implements 3 modes, which differ in how they handle a childs return value:

• The synchronous mode will try to succeed within one tick from its parent. If any child returns BehaviorState::Running, previous children will NOT be ticked again.
  • If a child returns BehaviorState::Failure, continue to the next sibling. If all the children fail, than this node returns BehaviorState::Failure.
  • If a child returns BehaviorState::Running, this node returns BehaviorState::Running and continues with the same child at the next tick from parent.
  • If a child returns BehaviorState::Success this behavior returns BehaviorState::Success.
• The asynchronous mode will return the flow contol after a childs failure to its parent. If any child returns BehaviorState::Running, previous children will NOT be ticked again.
  • If a the children returns BehaviorState::Failure, this node returns BehaviorState::Running. and continues with the next child at the next tick from parent. If all the children fail, than this node returns BehaviorState::Failure.
  • If a child returns BehaviorState::Running, this node returns BehaviorState::Running and continues with the same child at the next tick from parent.
  • If a child returns BehaviorState::Success this behavior returns BehaviorState::Success.
• The reactive mode always ticks all children from first to last: If any child returns BehaviorState::Running, previous children will be ticked again. IMPORTANT: Having asynchronous children (aka children that return BehaviorState::Running) makes this behavior difficult to predict. Avoid having more than one asynchronous children!
  • If a child returns BehaviorState::Running, continue to the next sibling.
  • If a child returns BehaviorState::Failure, continue to the next sibling. If all the children fail, than this node returns BehaviorState::Failure.
  • If a child returns BehaviorState::Success, stop running child and return BehaviorState::Success.

The variants are gated behind features fallback,async_fallback and reactive_fallback respectively.

Examples:

The synchronous variant is gated behind feature fallback.

<Fallback>
   <Behavior1/>
   <Behavior2/>
   <Behavior3/>
</Fallback>

The asynchronous variant is gated behind feature async_fallback.

<AsyncFallback>
   <Behavior1/>
   <Behavior2/>
   <Behavior3/>
</AsyncFallback>

Implementations

impl Fallbacks

pub const fn new(kind: FallbackKind) -> Self

Returns a Fallback behavior with the given kind.

pub fn create_fn(kind: FallbackKind) -> Box<BehaviorCreationFn>

Creates a creation_fn() for Fallback with the given kind.

pub fn register_with( registry: &mut impl BehaviorRegistry, name: &str, kind: FallbackKind, ) -> Result<(), Error>

Registers the Fallback behavior in the factory.

Errors

• if registration fails

Trait Implementations

impl Behavior for Fallbacks

fn on_start( &mut self, behavior: &mut BehaviorData, _children: &mut BehaviorTreeElementList, _runtime: &SharedRuntime, ) -> Result<(), Error>

Method is called before starting to tick a behavior, intended to do preliminary stuff for your behavior.

fn tick<'life0, 'life1, 'life2, 'life3, 'async_trait>( &'life0 mut self, _behavior: &'life1 mut BehaviorData, children: &'life2 mut BehaviorTreeElementList, runtime: &'life3 SharedRuntime, ) -> Pin<Box<dyn Future<Output = BehaviorResult> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait, 'life3: 'async_trait,

Method to tick a behavior.

fn on_halt(&mut self) -> Result<(), Error>

Method called during stop/cancel/halt of a behavior, intended to reset the internal fields of your behavior.

fn start<'life0, 'life1, 'life2, 'life3, 'async_trait>( &'life0 mut self, behavior: &'life1 mut BehaviorData, children: &'life2 mut BehaviorTreeElementList, runtime: &'life3 SharedRuntime, ) -> Pin<Box<dyn Future<Output = BehaviorResult> + Send + 'async_trait>>

where Self: 'async_trait, 'life0: 'async_trait, 'life1: 'async_trait, 'life2: 'async_trait, 'life3: 'async_trait,

Method is called on first tick of a behavior instead of tick(). If this method returns BehaviorState::Running, the behavior becomes asynchronous.

fn halt( &mut self, _behavior: &mut BehaviorData, children: &mut BehaviorTreeElementList, runtime: &SharedRuntime, ) -> BehaviorResult

Method to halt a behavior.

impl BehaviorExecution for Fallbacks

fn as_any(&self) -> &dyn Any

Dynamic downcasting.

fn as_any_mut(&mut self) -> &mut dyn Any

Mutable dynamic downcasting.

fn kind(&self) -> BehaviorKind

Get the BehaviorKind of the behavior.

fn portlist(&self) -> &dyn PortList

Access the PortList

fn portlist_mut(&mut self) -> &mut dyn PortList

Access the PortList

impl Debug for Fallbacks

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

Formats the value using the given formatter.

impl PortCollectionProvider for Fallbacks

fn provided_ports(&self) -> &impl PortCollectionAccessors

Returns immutable access to the collections entries.

fn provided_ports_mut(&mut self) -> &mut impl PortCollectionAccessors

Returns mutable access to the collections entries.

fn port_collection(&self) -> &impl PortCollection

Returns an immutable PortCollection.