Do not catch and rethrow exception from state handlers

fairmq/tools/Exceptions.h

@@ -0,0 +1,54 @@
+/********************************************************************************
+ *    Copyright (C) 2021 GSI Helmholtzzentrum fuer Schwerionenforschung GmbH    *
+ *                                                                              *
+ *              This software is distributed under the terms of the             *
+ *              GNU Lesser General Public Licence (LGPL) version 3,             *
+ *                  copied verbatim in the file "LICENSE"                       *
+ ********************************************************************************/
+
+#ifndef FAIR_MQ_TOOLS_EXCEPTIONS_H
+#define FAIR_MQ_TOOLS_EXCEPTIONS_H
+
+#include <functional>
+
+namespace fair::mq::tools
+{
+
+/**
+ * Executes the given callback in the destructor.
+ * Can be used to execute something in case of an exception when catch is undesirable, e.g.:
+ *
+ * {
+ *    // callback will be executed only if f throws an exception
+ *    CallOnDestruction cod([](){ cout << "exception was thrown"; }, true);
+ *    f();
+ *    cod.disable();
+ * }
+ */
+
+class CallOnDestruction
+{
+  public:
+    CallOnDestruction(std::function<void()> c, bool enable = true)
+        : callback(c)
+        , enabled(enable)
+    {}
+
+    ~CallOnDestruction()
+    {
+        if (enabled) {
+            callback();
+        }
+    }
+
+    void enable() { enabled = true; }
+    void disable() { enabled = false; }
+
+  private:
+    std::function<void()> callback;
+    bool enabled;
+};
+
+} // namespace fair::mq::tools
+
+#endif /* FAIR_MQ_TOOLS_EXCEPTIONS_H */