Add more specific exception types to the dynamic system and handle them properly

chaiscript/chaiscript_eval.hpp

@@ -110,7 +110,7 @@ namespace chaiscript
                         try {
                             retval = dispatch(ss.get_function(node->children[i+1]->text), plb);
                         }
-                        catch(std::exception &e){
+                        catch(const dispatchkit::dispatch_error &e){
                             throw EvalError("Can not find appropriate '" + node->children[i+1]->text + "'", node->children[i+1]);
                         }
                     }
@@ -136,7 +136,7 @@ namespace chaiscript
                         try {
                             retval = dispatch(ss.get_function(node->children[i]->text), plb);
                         }
-                        catch(std::exception &e){
+                        catch(const dispatchkit::dispatch_error &e){
                             throw EvalError("Can not find appropriate '" + node->children[i]->text + "'", node->children[i]);
                         }
                     }
@@ -155,7 +155,7 @@ namespace chaiscript
                     catch(std::out_of_range &oor) {
                         throw EvalError("Out of bounds exception", node);
                     }
-                    catch(std::exception &e){
+                    catch(const dispatchkit::dispatch_error &e){
                         throw EvalError("Can not find appropriate array lookup '[]'", node->children[i]);
                     }
                 }
@@ -208,12 +208,12 @@ namespace chaiscript
                             dispatchkit::Boxed_Value tmp = eval_token(ss, node->children[i]);
                             dispatch(ss.get_function("push_back"), dispatchkit::Param_List_Builder() << retval << tmp);
                         }
-                        catch (std::exception inner_e) {
+                        catch (const dispatchkit::dispatch_error &inner_e) {
                             throw EvalError("Can not find appropriate 'push_back'", node->children[i]);
                         }
                     }
                 }
-                catch (std::exception e) {
+                catch (const dispatchkit::dispatch_error &e) {
                     throw EvalError("Can not find appropriate 'Vector()'", node);
                 }
             }
@@ -227,12 +227,12 @@ namespace chaiscript
                             dispatchkit::Boxed_Value slot = dispatch(ss.get_function("[]"), dispatchkit::Param_List_Builder() << retval << key);
                             dispatch(ss.get_function("="), dispatchkit::Param_List_Builder() << slot << eval_token(ss, node->children[i]->children[1]));
                         }
-                        catch (std::exception inner_e) {
+                        catch (const dispatchkit::dispatch_error &inner_e) {
                             throw EvalError("Can not find appropriate '=' for map init", node->children[i]);
                         }
                     }
                 }
-                catch (std::exception e) {
+                catch (const dispatchkit::dispatch_error &e) {
                     throw EvalError("Can not find appropriate 'Vector()'", node);
                 }
             }
@@ -259,7 +259,7 @@ namespace chaiscript
                     ss.set_stack(prev_stack);
                     throw EvalError(ee.reason, node->children[0]);
                 }
-                catch(std::exception &e){
+                catch(const dispatchkit::dispatch_error &e){
                     ss.set_stack(prev_stack);
                     throw EvalError("Engine error: " + std::string(e.what()) + " on '" + node->children[0]->text + "'", node->children[0]);
                 }
@@ -304,7 +304,7 @@ namespace chaiscript
                             ss.set_stack(prev_stack);
                             throw EvalError(ee.reason, node);
                         }
-                        catch(std::exception &e){
+                        catch(const dispatchkit::dispatch_error &e){
                             ss.set_stack(prev_stack);
                             throw EvalError("Can not find appropriate '" + fun_name + "'", node);
                         }

dispatchkit/bootstrap.hpp

@@ -351,27 +351,6 @@ namespace dispatchkit
 
   }
 
-  class bad_boxed_value_cast : public std::bad_cast
-  {
-    public:
-      bad_boxed_value_cast(const std::string &val) throw()
-        : m_val(val)
-      {
-      }
-
-      virtual ~bad_boxed_value_cast() throw()
-      {
-      }
-
-      virtual const char * what() const throw()
-      {
-        return m_val.c_str();
-      }
-
-    private:
-      std::string m_val;
-  };
-
 
 
   //Built in to_string operator
@@ -420,7 +399,7 @@ namespace dispatchkit
       {
         return (lhs.assign(rhs));
       } else {
-        throw bad_boxed_value_cast("boxed_value has a set type alread");
+        throw bad_boxed_cast("boxed_value has a set type already");
       }
     }
 

dispatchkit/boxed_value.hpp

@@ -356,10 +356,40 @@ namespace dispatchkit
       }
     };
 
+  class bad_boxed_cast : public std::bad_cast
+  {
+    public:
+      bad_boxed_cast(const Type_Info &t_from, const std::type_info &t_to) throw()
+        : from(t_from.m_type_info), to(&t_to), m_what("Cannot perform boxed_cast")
+      {
+      }
+
+      bad_boxed_cast(const std::string &w) throw()
+        : m_what(w)
+      {
+      }
+
+      virtual ~bad_boxed_cast() throw() {}
+
+      virtual const char * what () throw()
+      {
+        return m_what.c_str();
+      }
+      const std::type_info *from;
+      const std::type_info *to;
+
+    private:
+      std::string m_what;
+  };
+
   template<typename Type>
   typename Cast_Helper<Type>::Result_Type boxed_cast(const Boxed_Value &bv)
   {
-    return Cast_Helper<Type>::cast(bv);
+    try {
+      return Cast_Helper<Type>::cast(bv);
+    } catch (const boost::bad_any_cast &) {
+      throw bad_boxed_cast(bv.get_type_info(), typeid(Type));
+    }
   }
 
   struct Boxed_POD_Value

dispatchkit/proxy_functions.hpp

@@ -13,6 +13,8 @@
 #include <string>
 #include <boost/function.hpp>
 #include <boost/bind.hpp>
+#include <boost/lexical_cast.hpp>
+
 #include <stdexcept>
 #include <vector>
 
@@ -88,6 +90,20 @@ namespace dispatchkit
 
     std::vector<Boxed_Value> objects;
   };
+
+  struct arity_error : std::range_error
+  {
+    arity_error(int t_got, int t_expected)
+      : std::range_error("Function dispatch arity mismatch"),
+        got(t_got), expected(t_expected)
+    {
+    }
+
+    virtual ~arity_error() throw() {}
+    int got;
+    int expected;
+  };
+
 }
 
 #define BOOST_PP_ITERATION_LIMITS ( 0, 10 )
@@ -96,6 +112,8 @@ namespace dispatchkit
 
 namespace dispatchkit
 {
+
+
   class Proxy_Function
   {
     public:
@@ -126,7 +144,7 @@ namespace dispatchkit
         {
           return m_f(params);
         } else {
-          throw std::range_error("Incorrect number of parameters");
+          throw arity_error(params.size(), m_arity);
         } 
       }
 
@@ -175,6 +193,16 @@ namespace dispatchkit
       Func m_f;
   };
 
+  struct dispatch_error : std::runtime_error
+  {
+    dispatch_error() throw()
+      : std::runtime_error("No matching function to dispatch to")
+    {
+    }
+
+    virtual ~dispatch_error() throw() {}
+  };
+
   Boxed_Value dispatch(const std::vector<std::pair<std::string, boost::shared_ptr<Proxy_Function> > > &funcs,
       const std::vector<Boxed_Value> &plist)
   {
@@ -184,14 +212,14 @@ namespace dispatchkit
     {
       try {
         return (*itr->second)(plist);
-      } catch (const std::bad_cast &) {
+      } catch (const bad_boxed_cast &) {
         //try again
-      } catch (const std::range_error &) {
+      } catch (const arity_error &) {
         //invalid num params, try again
       }
     }
 
-    throw std::runtime_error("No matching function to dispatch to");
+    throw dispatch_error();
   }
 }
 
@@ -210,7 +238,7 @@ namespace dispatchkit
 
       BOOST_PP_REPEAT(n, gettypeinfo, ~)
 
-        return ti;
+      return ti;
     }
 
   template<typename Ret BOOST_PP_COMMA_IF(n) BOOST_PP_ENUM_PARAMS(n, typename Param)>
@@ -219,7 +247,7 @@ namespace dispatchkit
     {
       if (params.size() != n)
       {
-        throw std::range_error("Incorrect number of parameters");
+        throw arity_error(params.size(), n);
       } else {
         return Handle_Return<Ret>()(boost::bind(f BOOST_PP_REPEAT(n, casthelper, ~)));
       }