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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...

Classes

struct  DummyBailOutChecker
 A dummy bail-out checker that always returns false. More...
 
struct  Iterator
 Iterates the listeners in a ListenerList. 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.
 
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 a member function on each listener in the list, with multiple parameters.
 
template<typename Callback >
void callExcluding (ListenerClass *listenerToExclude, Callback &&callback)
 Calls a member function with 1 parameter, on all but the specified listener in the list.
 
template<typename Callback , typename BailOutCheckerType >
void callChecked (const BailOutCheckerType &bailOutChecker, Callback &&callback)
 Calls a member function on each listener in the list, with 1 parameter and a bail-out-checker.
 
template<typename Callback , typename BailOutCheckerType >
void callCheckedExcluding (ListenerClass *listenerToExclude, const BailOutCheckerType &bailOutChecker, Callback &&callback)
 Calls a member function, with 1 parameter, on all but the specified listener in the list with a bail-out-checker.
 

Detailed Description

template<class ListenerClass, class ArrayType = Array<ListenerClass*>>
class 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() or callChecked().

E.g.

class MyListenerType
{
public:
void myCallbackMethod (int foo, bool bar);
};
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); });
Holds a set of objects and can invoke a member function callback on each object in the set with a sin...
Definition: juce_ListenerList.h:73
void add(ListenerClass *listenerToAdd)
Adds a listener to the list.
Definition: juce_ListenerList.h:94
void call(Callback &&callback)
Calls a member function on each listener in the list, with multiple parameters.
Definition: juce_ListenerList.h:138

It is guaranteed that every Listener is called during an iteration if it's inside the ListenerList before the iteration starts and isn't removed until its end. This guarantee holds even if some Listeners are removed or new ones are added during the iteration.

Listeners added during an iteration are guaranteed to be not called in that iteration.

Sometimes, there's a chance that invoking one of the callbacks might result in the list itself being deleted while it's still iterating - to survive this situation, you can use callChecked() instead of call(), passing it a local object to act as a "BailOutChecker". The BailOutChecker must implement a method of the form "bool shouldBailOut()", and the list will check this after each callback to determine whether it should abort the operation. For an example of a bail-out checker, see the Component::BailOutChecker class, which can be used to check when a Component has been deleted. See also ListenerList::DummyBailOutChecker, which is a dummy checker that always returns false.

Member Typedef Documentation

◆ ThisType

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

◆ ListenerType

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

Constructor & Destructor Documentation

◆ ListenerList()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
ListenerList< ListenerClass, ArrayType >::ListenerList ( )
default

Creates an empty list.

◆ ~ListenerList()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
ListenerList< ListenerClass, ArrayType >::~ListenerList ( )

Destructor.

Member Function Documentation

◆ add()

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

See also
remove

References jassertfalse.

◆ remove()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
void ListenerList< ListenerClass, ArrayType >::remove ( ListenerClass *  listenerToRemove)

Removes a listener from the list.

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

References jassert.

◆ size()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
int ListenerList< ListenerClass, ArrayType >::size ( ) const
noexcept

Returns the number of registered listeners.

Referenced by ListenerList< ListenerClass, ArrayType >::Iterator::next().

◆ isEmpty()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
bool ListenerList< ListenerClass, ArrayType >::isEmpty ( ) const
noexcept

Returns true if no listeners are registered, false otherwise.

◆ clear()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
void ListenerList< ListenerClass, ArrayType >::clear ( )

Clears the list.

◆ contains()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
bool ListenerList< ListenerClass, ArrayType >::contains ( ListenerClass *  listener) const
noexcept

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

◆ getListeners()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
const ArrayType & ListenerList< ListenerClass, ArrayType >::getListeners ( ) const
noexcept

Returns the raw array of listeners.

Referenced by ListenerList< ListenerClass, ArrayType >::Iterator::getListener().

◆ call()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
template<typename Callback >
void ListenerList< ListenerClass, ArrayType >::call ( Callback &&  callback)

Calls a member function on each listener in the list, with multiple parameters.

◆ callExcluding()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
template<typename Callback >
void ListenerList< ListenerClass, ArrayType >::callExcluding ( ListenerClass *  listenerToExclude,
Callback &&  callback 
)

Calls a member function with 1 parameter, on all but the specified listener in the list.

This can be useful if the caller is also a listener and needs to exclude itself.

◆ callChecked()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
template<typename Callback , typename BailOutCheckerType >
void ListenerList< ListenerClass, ArrayType >::callChecked ( const BailOutCheckerType &  bailOutChecker,
Callback &&  callback 
)

Calls a member function on each listener in the list, with 1 parameter and a bail-out-checker.

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

◆ callCheckedExcluding()

template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
template<typename Callback , typename BailOutCheckerType >
void ListenerList< ListenerClass, ArrayType >::callCheckedExcluding ( ListenerClass *  listenerToExclude,
const BailOutCheckerType &  bailOutChecker,
Callback &&  callback 
)

Calls a member function, with 1 parameter, on all but the specified listener in the list with a bail-out-checker.

This can be useful if the caller is also a listener and needs to exclude itself. See the class description for info about writing a bail-out checker.


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