libraries/JANA/JServiceFwd.h

0001
0002 #pragma once
0003 #include <JANA/Components/JComponentFwd.h>
0004
0005
0006 class JServiceLocator;
0007 struct JService : public jana::components::JComponent {
0008
0009     /// JServices may require other JServices, which may be loaded out of order from
0010     /// different plugins. For this reason, initialization of JServices is delayed until
0011     /// all plugins are loaded. Suppose you are writing Service B which depends on Service A.
0012     /// To acquire A during B's initialization, you should
0013     /// either declare a `Service<A> m_a_svc{this}` helper member, or fetch it manually by calling
0014     /// `GetApplication()->GetService<A>()` from inside `B::Init()`. Either way, the JServices will
0015     /// be initialized recursively and in the correct order.
0016     ///
0017     /// Note that historically JServices used the `acquire_services()` callback instead of `Init()`.
0018     /// While `acquire_services` hasn't been deprecated yet, it is on the roadmap, so we strongly
0019     /// recommend you override `Init()` instead.
0020     ///
0021     /// Note: Don't call JApplication::GetService<SvcT>() or JServiceLocator::get<SvcT>() from InitPlugin()!
0022
0023     virtual ~JService() = default;
0024
0025     // JService has its own DoInit() for the sake of acquire_services()
0026     void DoInit(JServiceLocator*);
0027
0028     // This will be deprecated eventually
0029     virtual void acquire_services(JServiceLocator*) {};
0030 };
0031