64 lines
2.5 KiB
C
64 lines
2.5 KiB
C
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/**
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\class Listener
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Derive your class from a Listener<EvType>, to give it the
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ability to hear (i.e. receive, listen to) events of type
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EvType. EvType is a fundamental type (bool, int, float,
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etc), a struct or a class of your choice. You must define
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Listener<EvType>::processEvent() in your Listener<EvType>
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subclass. You call listenForEvents() on your listener
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instance (at least once) for it to be able to hear (i.e.
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receive) any EvType event, and you call ignoreEvents() on
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the instance so it will no longer receive events of type
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EvType.
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\note
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- Do not assume that the Listeners will receive the generated event in
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the same order as they registered.
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- A class can listen to more than one type of event by inheriting
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from more than one type of listener. Calling listenForEvents()
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then is done by specifying which listenForEvents() to call, e.g.
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\code
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class YourListener:
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public Listener<TicEvent>, public Listener<TacEvent>
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{
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public:
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YourListener() {
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Listener<TicEvent>::listenForEvents();
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Listener<TacEvent>::listenForEvents();
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}
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protected:
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virtual void processEvent(const TicEvent& event) {...}
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virtual void processEvent(const TacEvent& event) {...}
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};
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\endcode
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- If a subclass of your class must also process an event, remember
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that because its processEvent is virtual, it will be the first
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one called. Therefore it should call its base class method:
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\code
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struct TicEvent {...};
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class YourListener: public Listener<TicEvent> {...};
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class DerivedListener: public YourListener
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{
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public:
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// ...
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protected:
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virtual void processEvent(const TicEvent& event)
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{
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// give parent class a chance to process event
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YourListener::processEvent(event);
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// do our stuff ...
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}
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};
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\endcode
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- ignoreThisEvent(): You can call it (from inside
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processEvent()) to tell EventSender<EvType> that you will be ignoring
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the event received. This can be a useful way to signify an error in
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the data sent by the event generator. Just keep in mind that the
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generator of the event may not actually check whether any listener
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ignored the event (it may not care).
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*/
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