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An interface can declare an observable object. This observable will notify observers (callback functions) when a certain event occurs.

用法

This interface declares the observable "ObservablePing" that will notify observers when the function "Ping" is called:

// This example shows an interface declaring an observable.

class ObserveMeInterface : MAXON_INTERFACE_BASES (maxon::ObserverObjectInterface) { MAXON_INTERFACE (ObserveMeInterface, MAXON_REFERENCE_NORMAL , "net.maxonexample.interfaces.observeme" );

public : //---------------------------------------------------------------------------------------- // Function makes "Ping". //---------------------------------------------------------------------------------------- MAXON_METHOD void Ping();

//---------------------------------------------------------------------------------------- // Signal fired when Ping() is called. //---------------------------------------------------------------------------------------- MAXON_OBSERVABLE ( void , ObservablePing, ( maxon::Int32 count), maxon::ObservableCombinerRunAllComponent); };

Such a callback function must have the same return value and argument list as defined in the observable declaration:

// This example shows a function that can be used as an observer. static void WatchPing( maxon::Int count) { DiagnosticOutput ( "Count: @" , count); }

The observable is accessible by the function of its name. An observer is added with maxon::ObservableBaseInterface::AddObserver() :

// This example adds an observer to the "ObservablePing" observable. g_observeMe.ObservablePing().AddObserver(WatchPing) iferr_return ;

It is also possible to add lambdas to the observable.

// This example adds a lambda to the "ObservablePing" observable. g_observeMe.ObservablePing().AddObserver( []( maxon::Int count) { DiagnosticOutput ( "Count: @" , count); }) iferr_return ;

The observer functions are called when the specific event is triggered.

// This example calls the Ping() function which will notify all registered observers. g_observeMe.Ping();