--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/OrthancStone/Sources/Messages/ObserverBase.h	Tue Jul 07 16:21:02 2020 +0200
@@ -0,0 +1,68 @@
+/**
+ * Stone of Orthanc
+ * Copyright (C) 2012-2016 Sebastien Jodogne, Medical Physics
+ * Department, University Hospital of Liege, Belgium
+ * Copyright (C) 2017-2020 Osimis S.A., Belgium
+ *
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU Affero General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ **/
+
+
+#pragma once
+
+#include "ICallable.h"
+#include "IObserver.h"
+#include "IObservable.h"
+
+#include <OrthancException.h>
+
+#include <boost/enable_shared_from_this.hpp>
+
+namespace OrthancStone 
+{
+  template <typename TObserver>
+  class ObserverBase : 
+    public IObserver,
+    public boost::enable_shared_from_this<TObserver>
+  {
+  public:
+    boost::shared_ptr<TObserver> GetSharedObserver()
+    {
+      try
+      {
+        return this->shared_from_this();
+      }
+      catch (boost::bad_weak_ptr&)
+      {
+        throw Orthanc::OrthancException(
+          Orthanc::ErrorCode_InternalError,
+          "Cannot get a shared pointer to an observer from its constructor, "
+          "or the observer is not created as a shared pointer");
+      }
+    }
+
+    template <typename TMessage>
+    ICallable* CreateCallable(void (TObserver::* MemberMethod) (const TMessage&))
+    {
+      return new Callable<TObserver, TMessage>(GetSharedObserver(), MemberMethod);
+    }
+
+    template <typename TMessage>
+    void Register(IObservable& observable,
+                  void (TObserver::* MemberMethod) (const TMessage&))
+    {
+      observable.RegisterCallable(CreateCallable(MemberMethod));
+    }
+  };
+}