Method trigger

example/E02-MockGUI.cpp:45–49

class ShowGEvent : public GEvent {
    CVoid trigger(GEventParamPtr param) override {
        auto p = CGRAPH_GET_GPARAM_WITH_NO_EMPTY(ProcessGParam, EXAMPLE_PARAM_KEY);
        CGRAPH_PARAM_READ_CODE_BLOCK(p);
        p->print();
    }
};