Event< T > Class Template Reference

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< Event >	Clone () 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 Event *	DoClone () const =0
	Derived classes must implement this method to clone themselves. More...
Implements CopyConstructible, CopyAssignable, MoveConstructible, MoveAssignable
	Event (const Event &)=default
Event &	operator= (const Event &)=default
	Event (Event &&)=default
Event &	operator= (Event &&)=default

Member Typedef Documentation

TriggerType

using TriggerType = systems::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

EventDataType

the 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

EventDataType

the 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

EventDataType

the 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

Returns true if this is a DiscreteUpdateEvent.

Implemented in UnrestrictedUpdateEvent< T >, DiscreteUpdateEvent< T >, and PublishEvent< T >.

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:

• drake/systems/framework/event.h