Simplified comm lifetime management (jupyter-xeus#701)

Author: JohanMabille

src/xcomm.cpp

@@ -83,7 +83,7 @@ namespace xpyt
         m_close_callback = std::move(callback);
         m_comm.on_close([this](const xeus::xmessage&)
         {
-            m_close_callback(comm_id());
+            m_close_callback();
         });
     }
 
@@ -128,7 +128,7 @@ namespace xpyt
             XPYT_HOLDING_GIL(py_callback(cppmessage_to_pymessage(msg)))
             if (m_close_callback)
             {
-                m_close_callback(comm_id());
+                m_close_callback();
             }
         };
     }
@@ -152,11 +152,10 @@ namespace xpyt
         // deletion by the garbage collector
         pycomm.inc_ref();
         xcomm& comm = pycomm.cast<xcomm&>();
-        comm.on_close_cleanup([this](std::string id)
+        comm.on_close_cleanup([pycomm]()
         {
-            XPYT_HOLDING_GIL(m_comms.erase(id))
+            XPYT_HOLDING_GIL(pycomm.dec_ref())
         });
-        m_comms[comm.comm_id()] = pycomm;
     }
 
     /***************

src/xcomm.hpp

@@ -21,7 +21,7 @@ namespace xpyt
     {
     public:
 
-        using close_callback_type = std::function<void(std::string)>;
+        using close_callback_type = std::function<void()>;
         using python_callback_type = std::function<void(py::object)>;
         using cpp_callback_type = std::function<void(const xeus::xmessage&)>;
         using buffers_sequence = xeus::buffer_sequence;
@@ -58,18 +58,12 @@ namespace xpyt
         close_callback_type m_close_callback;
     };
 
-    class xcomm_manager
+    struct xcomm_manager
     {
-    public:
-
         xcomm_manager() = default;
 
         void register_target(const py::str& target_name, const py::object& callback);
         void register_comm(py::object comm);
-
-    private:
-
-        std::map<std::string, py::object> m_comms;
     };
 
     py::module get_comm_module();