Drake
Drake C++ Documentation
Event< T > Class Template Referenceabstract

Detailed Description

template<typename T>
class drake::systems::Event< T >

Abstract base class that represents an event.

The base event contains two main pieces of information: an enum trigger type and an optional attribute that can be used to explain why the event is triggered.

Concrete derived classes contain a function pointer to an optional callback that handles the event. No-op is the default handling behavior. The System framework supports three concrete event types: PublishEvent, DiscreteUpdateEvent, and UnrestrictedUpdateEvent distinguished by their callback functions' write access level to the State.

The most common and convenient use of events and callbacks will happen via the LeafSystem Declare*Event() methods. To that end, the callback signature always passes the const System<T>& as the first argument, so that LeafSystem does not need to capture this into the lambda; typically only a pointer-to-member- function is captured. Capturing any more than that would defeat std::function's small buffer optimization and cause heap allocations when scheduling events.

Event handling occurs during a simulation of a system. The logic that describes when particular event types are handled is described in the class documentation for Simulator.

#include <drake/systems/framework/event.h>

Public Types

using TriggerType = systems::TriggerType
 

Public Member Functions

virtual ~Event ()=default
 
virtual bool is_discrete_update () const =0
 Returns true if this is a DiscreteUpdateEvent. More...
 
std::unique_ptr< EventClone () const
 Clones this instance. More...
 
TriggerType get_trigger_type () const
 Returns the trigger type. More...
 
template<typename EventDataType >
bool has_event_data () const
 Returns true if this event has associated data of the given EventDataType. More...
 
template<typename EventDataType >
const EventDataType * get_event_data () const
 Returns a const pointer to the event data. More...
 
template<typename EventDataType >
EventDataType * get_mutable_event_data ()
 Returns a mutable pointer to the event data. More...
 
void AddToComposite (TriggerType trigger_type, CompositeEventCollection< T > *events) const
 Adds a clone of this event to the event collection events, with the given trigger type. More...
 
void AddToComposite (CompositeEventCollection< T > *events) const
 Provides an alternate signature for adding an Event that already has the correct trigger type set. More...
 

Protected Member Functions

 Event ()=default
 Constructs an empty Event. More...
 
virtual void DoAddToComposite (TriggerType trigger_type, CompositeEventCollection< T > *events) const =0
 Derived classes must implement this to add a clone of this Event to the event collection and unconditionally set its trigger type. More...
 
virtual EventDoClone () const =0
 Derived classes must implement this method to clone themselves. More...
 
Implements CopyConstructible, CopyAssignable, MoveConstructible, MoveAssignable
 Event (const Event &)=default
 
Eventoperator= (const Event &)=default
 
 Event (Event &&)=default
 
Eventoperator= (Event &&)=default
 

Member Typedef Documentation

◆ TriggerType

Constructor & Destructor Documentation

◆ ~Event()

virtual ~Event ( )
virtualdefault

◆ Event() [1/3]

Event ( const Event< T > &  )
protecteddefault

◆ Event() [2/3]

Event ( Event< T > &&  )
protecteddefault

◆ Event() [3/3]

Event ( )
protecteddefault

Constructs an empty Event.

Member Function Documentation

◆ AddToComposite() [1/2]

void AddToComposite ( TriggerType  trigger_type,
CompositeEventCollection< T > *  events 
) const

Adds a clone of this event to the event collection events, with the given trigger type.

If this event has an unknown trigger type, then any trigger type is acceptable. Otherwise the given trigger type must match the trigger type stored in this event.

Precondition
trigger_type must match the current trigger type unless that is unknown.
events must not be null.

◆ AddToComposite() [2/2]

void AddToComposite ( CompositeEventCollection< T > *  events) const

Provides an alternate signature for adding an Event that already has the correct trigger type set.

Must not have an unknown trigger type.

◆ Clone()

std::unique_ptr<Event> Clone ( ) const

Clones this instance.

◆ DoAddToComposite()

virtual void DoAddToComposite ( TriggerType  trigger_type,
CompositeEventCollection< T > *  events 
) const
protectedpure virtual

Derived classes must implement this to add a clone of this Event to the event collection and unconditionally set its trigger type.

◆ DoClone()

virtual Event* DoClone ( ) const
protectedpure virtual

Derived classes must implement this method to clone themselves.

Any Event-specific data is cloned using the Clone() method. Data specific to the class derived from Event must be cloned by the implementation.

◆ get_event_data()

const EventDataType* get_event_data ( ) const

Returns a const pointer to the event data.

The returned value can be nullptr, which means this event does not have any associated data of the given EventDataType.

Template Parameters
EventDataTypethe expected data type for an event that has this trigger type (PeriodicEventData or WitnessTriggeredEventData).

◆ get_mutable_event_data()

EventDataType* get_mutable_event_data ( )

Returns a mutable pointer to the event data.

The returned value can be nullptr, which means this event does not have any associated data of the given EventDataType.

Template Parameters
EventDataTypethe expected data type for an event that has this trigger type (PeriodicEventData or WitnessTriggeredEventData).

◆ get_trigger_type()

TriggerType get_trigger_type ( ) const

Returns the trigger type.

◆ has_event_data()

bool has_event_data ( ) const

Returns true if this event has associated data of the given EventDataType.

Template Parameters
EventDataTypethe expected data type for an event that has this trigger type (PeriodicEventData or WitnessTriggeredEventData).

◆ is_discrete_update()

virtual bool is_discrete_update ( ) const
pure virtual

◆ operator=() [1/2]

Event& operator= ( Event< T > &&  )
protecteddefault

◆ operator=() [2/2]

Event& operator= ( const Event< T > &  )
protecteddefault

The documentation for this class was generated from the following file: