Observer

with ZFCallback available, it's easy to use observer mechanism

zfclass MyObject : zfextend ZFObject {
    ZFOBJECT_DECLARE(MyObject, ZFObject)
 
    ZFOBSERVER_EVENT(MyEvent)
 
public:
    void test(void) {
        zfobj<ZFObject> myParam0;
        zfobj<ZFObject> myParam1;
        this->observerNotify(
            MyObject::EventMyEvent(), // event id to notify
            myParam0, // param0
            myParam1); // param1
    }
};
static void testListener1(ZF_IN const ZFArgs &zfargs) {
    zfLog()
        << zfargs.sender() // should be MyObject
        << zfargs.param0() // should be myParam0 passed from observerNotify
        << zfargs.param1() // should be myParam1 passed from observerNotify
        ;
}
static void testListener2(
        ZF_IN const ZFArgs &zfargs
        , ZF_IN v_zfstring *myUserData
        ) {
    zfLog()
        << zfargs.sender() // should be MyObject
        << zfargs.param0() // should be myParam0 passed from observerNotify
        << zfargs.param1() // should be myParam1 passed from observerNotify
        << myUserData // should be myUserData passed from observer
        ;
}

// the object to test observer
zfobj<MyObject> obj;
// the object to test user data passing
zfobj<v_zfstring> myUserData("myUserData");
 
// we use ZFListener as observer callback type,
// which takes two param as ZFArgs and ZFObject,
// to create it,
// use ZFCallbackForXXX series same as ZFCallback
ZFListener listener1 = ZFCallbackForFunc(testListener1);
 
// add an observer
obj->observerAdd(MyObject::EventMyEvent(), listener1);
 
// optionally, you may declare a lambda-like listener for short
// or, for extra param passing
ZFLISTENER_1(listener2
        , zfautoT<v_zfstring>, myUserData
        ) {
    testListener2(zfargs, myUserData);
} ZFLISTENER_END()
obj->observerAdd(MyObject::EventMyEvent(), listener2);
 
// finlly we will test to notify the event
obj->test();
 
// or, you may notify it manually
// but it's your responsibility to ensure the passed params suit for the listener
zfobj<ZFObject> myParam0;
zfobj<ZFObject> myParam1;
obj->observerNotify(MyObject::EventMyEvent(), myParam0, myParam1);