Make EvalError a subclass of runtime_error and provide the std::exception with a robust description for easier debugging of callback/scripted function calls

chaiscript/chaiscript_engine.hpp

@@ -29,12 +29,12 @@ namespace chaiscript
             try {
                 val = dispatchkit::Cast_Helper<std::string &>()(vals[0]);
             }
-            catch (std::exception &e) {
-                throw EvalError("Can not evaluate string: " + val, langkit::TokenPtr());
-            }
             catch (EvalError &ee) {
                 throw EvalError("Can not evaluate string: " + val + " reason: " + ee.reason, langkit::TokenPtr());
             }
+            catch (std::exception &e) {
+                throw EvalError("Can not evaluate string: " + val, langkit::TokenPtr());
+            }
             return evaluate_string(val);
         }
 

chaiscript/chaiscript_eval.hpp

@@ -15,11 +15,16 @@ namespace chaiscript
         ParserError(const std::string &why, const langkit::TokenPtr where) : reason(why), location(where){ }
     };
 
-    struct EvalError {
+    struct EvalError : public std::runtime_error {
         std::string reason;
         langkit::TokenPtr location;
 
-        EvalError(const std::string &why, const langkit::TokenPtr where) : reason(why), location(where) { }
+        EvalError(const std::string &why, const langkit::TokenPtr where) 
+          : std::runtime_error("Eval error: \"" + why + "\" in '" 
+              + where->filename + "' line: " + boost::lexical_cast<std::string>(where->start.line+1)), 
+            reason(why), location(where) { }
+
+        virtual ~EvalError() throw() {}
     };
 
     struct ReturnValue {

samples/callbacks.chai

@@ -4,4 +4,5 @@ cb_handler.add_callbacks( function() { "DivOnePtTwo"; }, function (x) { x / 1.2;
 
 
 
+cb_handler.add_callbacks( function() { "DivOnePtTwo"; }, function (x) { blargh; } );