Make ExceptionAbstract::getCode() const.

include/dynamic-graph/exception-abstract.h

@@ -78,7 +78,7 @@ public:
   virtual ~ExceptionAbstract( void ) throw() {}
 
   /**  Access to the error code. */
-  int getCode (void);
+  int getCode () const;
 
   /** Reference access to the error message (can be empty). */
   const std::string& getStringMessage (void) const;

src/exception/exception-abstract.cpp

@@ -59,8 +59,8 @@ getStringMessage (void) const
     return this->message;
 }
 
-int ExceptionAbstract::
-getCode (void)
+int
+ExceptionAbstract::getCode () const
 {
     return this->code;
 }