Director exceptions now derive from std::exception

Lib/csharp/director.swg

@@ -9,6 +9,7 @@
 #include <iostream>
 #endif
 #include <string>
+#include <exception>
 
 namespace Swig {
   /* Director base class - not currently used in C# directors */
@@ -16,7 +17,7 @@ namespace Swig {
   };
 
   /* Base class for director exceptions */
-  class DirectorException {
+  class DirectorException : public std::exception {
   protected:
     std::string swig_msg;
 
@@ -27,16 +28,16 @@ namespace Swig {
     DirectorException(const std::string &msg) : swig_msg(msg) {
     }
 
-    const std::string& what() const {
-      return swig_msg;
+    virtual ~DirectorException() throw() {
     }
 
-    virtual ~DirectorException() {
+    const char *what() const throw() {
+      return swig_msg.c_str();
     }
   };
 
   /* Pure virtual method exception */
-  class DirectorPureVirtualException : public Swig::DirectorException {
+  class DirectorPureVirtualException : public DirectorException {
   public:
     DirectorPureVirtualException(const char *msg) : DirectorException(std::string("Attempt to invoke pure virtual method ") + msg) {
     }