backmerge PR #189 into release/v0.4.0

* upstream/pr/189/head:
  fix error messages

Signed-off-by: Torbjörn Klatt <[email protected]>

Author: torbjoernk

include/pfasst/interfaces.hpp

@@ -29,9 +29,6 @@ namespace pfasst
   class NotImplementedYet
     : public runtime_error
   {
-    protected:
-      string msg;
-
     public:
       /**
        * @param[in] msg component or algorithm the throwing function is required for
@@ -53,9 +50,6 @@ namespace pfasst
   class ValueError
     : public invalid_argument
   {
-    protected:
-      string msg;
-
     public:
       explicit ValueError(const string& msg);
       virtual const char* what() const throw();

src/pfasst/interfaces_impl.hpp

@@ -21,7 +21,7 @@ namespace pfasst
    */
   const char* NotImplementedYet::what() const throw()
   {
-    return (string("Not implemented/supported yet, required for: ") + this->msg).c_str();
+    return (string("Not implemented/supported yet, required for: ") + string(runtime_error::what())).c_str();
   }
 
 
@@ -36,7 +36,7 @@ namespace pfasst
    */
   const char* ValueError::what() const throw()
   {
-    return (string("ValueError: ") + this->msg).c_str();
+    return (string("ValueError: ") + string(invalid_argument::what())).c_str();
   }