WIP: start to design the dE/dx simulation tool.

Simulation/DetSimInterface/DetSimInterface/IDedxSimTool.h

+#ifndef IDedxSimTool_h
+#define IDedxSimTool_h
+
+/*
+ * Description:
+ *   IDedxSimTool is used to give a dE/dx value during simulation.
+ *
+ * The interface:
+ *   * dedx: predict the dE/dx according to Geant4 Step
+ *
+ * Author: Tao Lin <lintao@ihep.ac.cn>
+ */
+
+
+#include "GaudiKernel/IAlgTool.h"
+
+class G4Step;
+
+class IDedxSimTool: virtual public IAlgTool {
+public:
+
+    DeclareInterfaceID(IDedxSimTool, 0, 1);
+    virtual ~IDedxSimTool() {}
+
+    virtual double dedx(const G4Step* aStep) = 0;
+
+};
+
+#endif