--- a/Sources/OnStoredInstanceCallback.cpp	Fri Jun 11 14:13:36 2021 +0200
+++ b/Sources/OnStoredInstanceCallback.cpp	Fri Jun 11 14:34:08 2021 +0200
@@ -19,10 +19,10 @@
 
 #include "OnStoredInstanceCallback.h"
 
-#include "PythonString.h"
+#include "../Resources/Orthanc/Plugins/OrthancPluginCppWrapper.h"
 #include "Autogenerated/sdk.h"
-
-#include "../Resources/Orthanc/Plugins/OrthancPluginCppWrapper.h"
+#include "ICallbackRegistration.h"
+#include "PythonString.h"
 
 
 static PyObject*   storedInstanceCallback_ = NULL;
@@ -78,42 +78,24 @@
 PyObject* RegisterOnStoredInstanceCallback(PyObject* module, PyObject* args)
 {
   // The GIL is locked at this point (no need to create "PythonLock")
-  
-  // https://docs.python.org/3/extending/extending.html#calling-python-functions-from-c
-  PyObject* callback = NULL;
 
-  if (!PyArg_ParseTuple(args, "O", &callback) ||
-      callback == NULL)
-  {
-    PyErr_SetString(PyExc_ValueError, "Expected a callback function");
-    return NULL;
-  }
-
-  if (storedInstanceCallback_ != NULL)
+  class Registration : public ICallbackRegistration
   {
-    PyErr_SetString(PyExc_RuntimeError, "Can only register one Python on-stored-instance callback");
-    return NULL;
-  }
-  
-  OrthancPlugins::LogInfo("Registering a Python on-stored-instance callback");
+  public:
+    virtual void Register() ORTHANC_OVERRIDE
+    {
+      OrthancPluginRegisterOnStoredInstanceCallback(
+        OrthancPlugins::GetGlobalContext(), OnStoredInstanceCallback);
+    }
+  };
 
-  OrthancPluginRegisterOnStoredInstanceCallback(
-    OrthancPlugins::GetGlobalContext(), OnStoredInstanceCallback);
-
-  storedInstanceCallback_ = callback;
-  Py_XINCREF(storedInstanceCallback_);
-  
-  Py_INCREF(Py_None);
-  return Py_None;
+  Registration registration;
+  return ICallbackRegistration::Apply(
+    registration, args, storedInstanceCallback_, "Python on-stored-instance callback");
 }
 
 
 void FinalizeOnStoredInstanceCallback()
 {
-  PythonLock lock;
-        
-  if (storedInstanceCallback_ != NULL)
-  {
-    Py_XDECREF(storedInstanceCallback_);
-  }
+  ICallbackRegistration::Unregister(storedInstanceCallback_);
 }