juce::ListenerList< ListenerClass, ArrayType > Class Template Reference

Holds a set of objects and can invoke a member function callback on each object in the set with a single call. More...

#include "juce_ListenerList.h"

Classes
struct	DummyBailOutChecker
	A dummy bail-out checker that always returns false. More...

Public Types
using	ThisType = ListenerList< ListenerClass, ArrayType >
using	ListenerType = ListenerClass

Public Member Functions
	ListenerList ()=default
	Creates an empty list.
	~ListenerList ()
	Destructor.
void	add (ListenerClass *listenerToAdd)
	Adds a listener to the list.
void	remove (ListenerClass *listenerToRemove)
	Removes a listener from the list.
ErasedScopeGuard	addScoped (ListenerClass &listenerToAdd)
	Adds a listener that will be automatically removed again when the Guard is destroyed.
int	size () const noexcept
	Returns the number of registered listeners.
bool	isEmpty () const noexcept
	Returns true if no listeners are registered, false otherwise.
void	clear ()
	Clears the list.
bool	contains (ListenerClass *listener) const noexcept
	Returns true if the specified listener has been added to the list.
const ArrayType &	getListeners () const noexcept
	Returns the raw array of listeners.
template<typename Callback >
void	call (Callback &&callback)
	Calls an invokable object for each listener in the list.
template<typename Callback >
void	callExcluding (ListenerClass *listenerToExclude, Callback &&callback)
	Calls an invokable object for each listener in the list, except for the listener specified by listenerToExclude.
template<typename Callback , typename BailOutCheckerType >
void	callChecked (const BailOutCheckerType &bailOutChecker, Callback &&callback)
	Calls an invokable object for each listener in the list, additionally checking the bail-out checker before each call.
template<typename Callback , typename BailOutCheckerType >
void	callCheckedExcluding (ListenerClass *listenerToExclude, const BailOutCheckerType &bailOutChecker, Callback &&callback)
	Calls an invokable object for each listener in the list, except for the listener specified by listenerToExclude, additionally checking the bail-out checker before each call.
template<typename... MethodArgs, typename... Args>
void	call (void(ListenerClass::*callbackFunction)(MethodArgs...), Args &&... args)
	Calls a specific listener method for each listener in the list.
template<typename... MethodArgs, typename... Args>
void	callExcluding (ListenerClass *listenerToExclude, void(ListenerClass::*callbackFunction)(MethodArgs...), Args &&... args)
	Calls a specific listener method for each listener in the list, except for the listener specified by listenerToExclude.
template<typename BailOutCheckerType , typename... MethodArgs, typename... Args>
void	callChecked (const BailOutCheckerType &bailOutChecker, void(ListenerClass::*callbackFunction)(MethodArgs...), Args &&... args)
	Calls a specific listener method for each listener in the list, additionally checking the bail-out checker before each call.
template<typename BailOutCheckerType , typename... MethodArgs, typename... Args>
void	callCheckedExcluding (ListenerClass *listenerToExclude, const BailOutCheckerType &bailOutChecker, void(ListenerClass::*callbackFunction)(MethodArgs...), Args &&... args)
	Calls a specific listener method for each listener in the list, except for the listener specified by listenerToExclude, additionally checking the bail-out checker before each call.

Detailed Description

template<class ListenerClass, class ArrayType = Array<ListenerClass*>>
class juce::ListenerList< ListenerClass, ArrayType >

Holds a set of objects and can invoke a member function callback on each object in the set with a single call.

Use a ListenerList to manage a set of objects which need a callback, and you can invoke a member function by simply calling call(), callChecked(), or callExcluding().

E.g.

class MyListenerType
{
public:
    void myCallbackMethod (int foo, bool bar);
};
 
ListenerList<MyListenerType> listeners;
listeners.add (someCallbackObjects...);
 
// This will invoke myCallbackMethod (1234, true) on each of the objects
// in the list...
listeners.call ([] (MyListenerType& l) { l.myCallbackMethod (1234, true); });

It is safe to add listeners, remove listeners, clear the listeners, and delete the ListenerList itself during any listener callback.

If a Listener is added during a callback, it is guaranteed not to be called in the same iteration.

If a Listener is removed during a callback, it is guaranteed not to be called if it hasn't already been called.

If the ListenerList is cleared or deleted during a callback, it is guaranteed that no more listeners will be called.

By default a ListenerList is not thread safe. If thread-safety is required, you can provide a thread-safe Array type as the second type parameter e.g.

using ThreadSafeList = ListenerList<MyListenerType, Array<MyListenerType*, CriticalSection>>;

When calling listeners the iteration can be escaped early by using a "BailOutChecker". A BailOutChecker is a type that has a public member function with the following signature:

bool shouldBailOut() const 

This function will be called before making a call to each listener. For an example see the DummyBailOutChecker.

@tags{Core}

Definition at line 80 of file juce_ListenerList.h.

Member Typedef Documentation

ListenerType

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

using juce::ListenerList< ListenerClass, ArrayType >::ListenerType = ListenerClass

Definition at line 322 of file juce_ListenerList.h.

ThisType

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

using juce::ListenerList< ListenerClass, ArrayType >::ThisType = ListenerList<ListenerClass, ArrayType>

Definition at line 321 of file juce_ListenerList.h.

Constructor & Destructor Documentation

~ListenerList()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

juce::ListenerList< ListenerClass, ArrayType >::~ListenerList

(

)

Destructor.

Definition at line 88 of file juce_ListenerList.h.

Member Function Documentation

add()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

void juce::ListenerList< ListenerClass, ArrayType >::add

(

ListenerClass *

listenerToAdd

)

Adds a listener to the list.

A listener can only be added once, so if the listener is already in the list, this method has no effect.

If a Listener is added during a callback, it is guaranteed not to be called in the same iteration.

See also

remove

Definition at line 100 of file juce_ListenerList.h.

addScoped()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

ErasedScopeGuard juce::ListenerList< ListenerClass, ArrayType >::addScoped

(

ListenerClass &

listenerToAdd

)

Adds a listener that will be automatically removed again when the Guard is destroyed.

Be very careful to ensure that the ErasedScopeGuard is destroyed or released before the ListenerList is destroyed, otherwise the ErasedScopeGuard may attempt to dereference a dangling pointer when it is destroyed, which will result in a crash.

Definition at line 138 of file juce_ListenerList.h.

call() [1/2]

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

template<typename Callback >

void juce::ListenerList< ListenerClass, ArrayType >::call

(

Callback &&

callback

)

Calls an invokable object for each listener in the list.

Definition at line 182 of file juce_ListenerList.h.

call() [2/2]

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

template<typename... MethodArgs, typename... Args>

void juce::ListenerList< ListenerClass, ArrayType >::call	(	void(ListenerClass::*)(MethodArgs...)	callbackFunction,
		Args &&...	args
	)

Calls a specific listener method for each listener in the list.

Definition at line 255 of file juce_ListenerList.h.

callChecked() [1/2]

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

template<typename Callback , typename BailOutCheckerType >

void juce::ListenerList< ListenerClass, ArrayType >::callChecked	(	const BailOutCheckerType &	bailOutChecker,
		Callback &&	callback
	)

Calls an invokable object for each listener in the list, additionally checking the bail-out checker before each call.

See the class description for info about writing a bail-out checker.

Definition at line 207 of file juce_ListenerList.h.

callChecked() [2/2]

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

template<typename BailOutCheckerType , typename... MethodArgs, typename... Args>

void juce::ListenerList< ListenerClass, ArrayType >::callChecked	(	const BailOutCheckerType &	bailOutChecker,
		void(ListenerClass::*)(MethodArgs...)	callbackFunction,
		Args &&...	args
	)

Calls a specific listener method for each listener in the list, additionally checking the bail-out checker before each call.

See the class description for info about writing a bail-out checker.

Definition at line 283 of file juce_ListenerList.h.

callCheckedExcluding() [1/2]

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

template<typename Callback , typename BailOutCheckerType >

void juce::ListenerList< ListenerClass, ArrayType >::callCheckedExcluding	(	ListenerClass *	listenerToExclude,
		const BailOutCheckerType &	bailOutChecker,
		Callback &&	callback
	)

Calls an invokable object for each listener in the list, except for the listener specified by listenerToExclude, additionally checking the bail-out checker before each call.

See the class description for info about writing a bail-out checker.

Definition at line 221 of file juce_ListenerList.h.

callCheckedExcluding() [2/2]

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

template<typename BailOutCheckerType , typename... MethodArgs, typename... Args>

void juce::ListenerList< ListenerClass, ArrayType >::callCheckedExcluding	(	ListenerClass *	listenerToExclude,
		const BailOutCheckerType &	bailOutChecker,
		void(ListenerClass::*)(MethodArgs...)	callbackFunction,
		Args &&...	args
	)

Calls a specific listener method for each listener in the list, except for the listener specified by listenerToExclude, additionally checking the bail-out checker before each call.

See the class description for info about writing a bail-out checker.

Definition at line 300 of file juce_ListenerList.h.

callExcluding() [1/2]

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

template<typename Callback >

void juce::ListenerList< ListenerClass, ArrayType >::callExcluding	(	ListenerClass *	listenerToExclude,
		Callback &&	callback
	)

Calls an invokable object for each listener in the list, except for the listener specified by listenerToExclude.

Definition at line 193 of file juce_ListenerList.h.

callExcluding() [2/2]

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

template<typename... MethodArgs, typename... Args>

void juce::ListenerList< ListenerClass, ArrayType >::callExcluding	(	ListenerClass *	listenerToExclude,
		void(ListenerClass::*)(MethodArgs...)	callbackFunction,
		Args &&...	args
	)

Calls a specific listener method for each listener in the list, except for the listener specified by listenerToExclude.

Definition at line 267 of file juce_ListenerList.h.

clear()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

void juce::ListenerList< ListenerClass, ArrayType >::clear

(

)

Clears the list.

If the ListenerList is cleared during a callback, it is guaranteed that no more listeners will be called.

Definition at line 155 of file juce_ListenerList.h.

contains()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

bool juce::ListenerList< ListenerClass, ArrayType >::contains ( ListenerClass *  listener ) const

noexcept

Returns true if the specified listener has been added to the list.

Definition at line 166 of file juce_ListenerList.h.

getListeners()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

const ArrayType & juce::ListenerList< ListenerClass, ArrayType >::getListeners ( ) const

noexcept

Returns the raw array of listeners.

Any attempt to mutate the array may result in undefined behaviour.

If the array uses a mutex/CriticalSection, reading from the array without first obtaining the lock may potentially result in undefined behaviour.

See also

add, remove, clear, contains

Definition at line 177 of file juce_ListenerList.h.

isEmpty()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

bool juce::ListenerList< ListenerClass, ArrayType >::isEmpty ( ) const

noexcept

Returns true if no listeners are registered, false otherwise.

Definition at line 148 of file juce_ListenerList.h.

remove()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

void juce::ListenerList< ListenerClass, ArrayType >::remove

(

ListenerClass *

listenerToRemove

)

Removes a listener from the list.

If the listener wasn't in the list, this has no effect.

If a Listener is removed during a callback, it is guaranteed not to be called if it hasn't already been called.

Definition at line 114 of file juce_ListenerList.h.

size()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>

int juce::ListenerList< ListenerClass, ArrayType >::size ( ) const

noexcept

Returns the number of registered listeners.

Definition at line 145 of file juce_ListenerList.h.

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

• juce_core/containers/juce_ListenerList.h