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

## Detailed Description

template<typename ListenerClass, typename 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.

It is safe to add listeners, remove listeners, clear the listeners, and even delete the ListenerList itself during any listener callback. If you don't need these extra guarantees consider using a LightweightListenerList instead.

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.

It is NOT safe to make concurrent calls to the listeners without a mutex. If you need this functionality, either use a LightweightListenerList or a ThreadSafeListenerList.

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.

See also
  LightweightListenerList, ThreadSafeListenerList

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

- juce_core/containers/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.

## Member Typedef Documentation

## ThisType

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

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

## ListenerType

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

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

## Constructors and Destructors

## ListenerList()

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

juce::ListenerList< ListenerClass, ArrayType >::ListenerList | ( |  | ) |

default

Creates an empty list.

## ~ListenerList()

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

juce::ListenerList< ListenerClass, ArrayType >::~ListenerList | ( |  | ) |

inline

Destructor.

## Member Functions

## add()

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

void juce::ListenerList< ListenerClass, ArrayType >::add | ( | ListenerClass * | listenerToAdd | ) |

inline

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

Referenced by addScoped().

## remove()

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

void juce::ListenerList< ListenerClass, ArrayType >::remove | ( | ListenerClass * | listenerToRemove | ) |

inline

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.

Referenced by addScoped().

## addScoped()

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

ErasedScopeGuard juce::ListenerList< ListenerClass, ArrayType >::addScoped | ( | ListenerClass & | listenerToAdd | ) |

inline nodiscard

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.

## size()

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

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

inline nodiscard noexcept

Returns the number of registered listeners.

## isEmpty()

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

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

inline nodiscard noexcept

Returns true if no listeners are registered, false otherwise.

## clear()

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

void juce::ListenerList< ListenerClass, ArrayType >::clear | ( |  | ) |

inline

Clears the list.

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

Referenced by ~ListenerList().

## contains()

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

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

inline nodiscard noexcept

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

## getListeners()

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

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

inline nodiscard 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

## call() [1/2]

template<typename ListenerClass, typename ArrayType = Array<ListenerClass*>>
template<typename Callback>

void juce::ListenerList< ListenerClass, ArrayType >::call | ( | Callback && | callback | ) |

inline

Calls an invokable object for each listener in the list.

## callExcluding() [1/2]

template<typename ListenerClass, typename ArrayType = Array<ListenerClass*>>
template<typename Callback>

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

inline

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

## callChecked() [1/2]

template<typename ListenerClass, typename ArrayType = Array<ListenerClass*>>
template<typename Callback, typename BailOutCheckerType>

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

inline

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.

## callCheckedExcluding() [1/2]

template<typename ListenerClass, typename ArrayType = Array<ListenerClass*>>
template<typename Callback, typename BailOutCheckerType>

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

inline

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.

Referenced by call(), call(), callChecked(), callChecked(), callCheckedExcluding(), callCheckedExcluding(), callExcluding(), and callExcluding().

## call() [2/2]

template<typename ListenerClass, typename ArrayType = Array<ListenerClass*>>
template<typename... MethodArgs, typename... Args>

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

inline

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

## callExcluding() [2/2]

template<typename ListenerClass, typename ArrayType = Array<ListenerClass*>>
template<typename... MethodArgs, typename... Args>

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

inline

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

## callChecked() [2/2]

template<typename ListenerClass, typename ArrayType = Array<ListenerClass*>>
template<typename BailOutCheckerType, typename... MethodArgs, typename... Args>

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

inline

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.

## callCheckedExcluding() [2/2]

template<typename ListenerClass, typename ArrayType = Array<ListenerClass*>>
template<typename BailOutCheckerType, typename... MethodArgs, typename... Args>

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

inline

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.

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