Holds a set of objects and can invoke a member function callback on each object in the set with a single call.
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| ListenerList ()=default |
| Creates an empty list. More...
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| ~ListenerList ()=default |
| Destructor. More...
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void | add (ListenerClass *listenerToAdd) |
| Adds a listener to the list. More...
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template<typename Callback > |
void | call (Callback &&callback) |
| Calls a member function on each listener in the list, with multiple parameters. More...
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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. More...
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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. More...
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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. More...
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void | clear () |
| Clears the list. More...
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bool | contains (ListenerClass *listener) const noexcept |
| Returns true if the specified listener has been added to the list. More...
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const ArrayType & | getListeners () const noexcept |
| Returns the raw array of listeners. More...
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bool | isEmpty () const noexcept |
| Returns true if no listeners are registered, false otherwise. More...
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void | remove (ListenerClass *listenerToRemove) |
| Removes a listener from the list. More...
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int | size () const noexcept |
| Returns the number of registered listeners. More...
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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() or callChecked().
E.g.
class MyListenerType
{
public:
void myCallbackMethod (int foo, bool bar);
};
listeners.call ([] (MyListenerType& l) { l.myCallbackMethod (1234,
true); });
If you add or remove listeners from the list during one of the callbacks - i.e. while it's in the middle of iterating the listeners, then it's guaranteed that no listeners will be mistakenly called after they've been removed, but it may mean that some of the listeners could be called more than once, or not at all, depending on the list's order.
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.
@tags{Core}
template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
template<typename Callback , typename BailOutCheckerType >
void juce::ListenerList< ListenerClass, ArrayType >::callChecked |
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const BailOutCheckerType & |
bailOutChecker, |
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Callback && |
callback |
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) |
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inline |
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.
template<class ListenerClass , class ArrayType = Array<ListenerClass*>>
template<typename Callback , typename BailOutCheckerType >
void juce::ListenerList< ListenerClass, ArrayType >::callCheckedExcluding |
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ListenerClass * |
listenerToExclude, |
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const BailOutCheckerType & |
bailOutChecker, |
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Callback && |
callback |
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) |
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inline |
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.