Nasal cppbind: support more member function types

simgear/nasal/cppbind/Ghost.hxx

@@ -357,15 +357,15 @@ namespace nasal
        * @param setter  Setter for variable (Pass 0 to prevent write access)
        *
        */
-      template<class Var>
+      template<class Ret, class Param>
       Ghost& member( const std::string& field,
-                     Var (raw_type::*getter)() const,
+                     Ret (raw_type::*getter)() const,
-                     void (raw_type::*setter)(typename boost::call_traits<Var>::param_type) = 0 )
+                     void (raw_type::*setter)(Param) )
       {
         member_t m;
         if( getter )
         {
-          typedef typename boost::call_traits<Var>::param_type param_type;
+          typedef typename boost::call_traits<Ret>::param_type param_type;
           naRef (*to_nasal_)(naContext, param_type) = &nasal::to_nasal;
 
           // Getter signature: naRef(naContext, raw_type&)
@@ -374,7 +374,8 @@ namespace nasal
 
         if( setter )
         {
-          Var (*from_nasal_)(naContext, naRef) = &nasal::from_nasal;
+          typename boost::remove_reference<Param>::type
+          (*from_nasal_)(naContext, naRef) = &nasal::from_nasal;
 
           // Setter signature: void(naContext, raw_type&, naRef)
           m.setter = boost::bind(setter, _2, boost::bind(from_nasal_, _1, _3));
@@ -383,6 +384,19 @@ namespace nasal
         return member(field, m.getter, m.setter);
       }
 
+      /**
+       * Register a read only member variable.
+       *
+       * @param field   Name of member
+       * @param getter  Getter for variable
+       */
+      template<class Ret>
+      Ghost& member( const std::string& field,
+                     Ret (raw_type::*getter)() const )
+      {
+        return member<Ret, Ret>(field, getter, 0);
+      }
+
       /**
        * Register a write only member variable.
        *
@@ -393,7 +407,7 @@ namespace nasal
       Ghost& member( const std::string& field,
                      void (raw_type::*setter)(Var) )
       {
-        return member<Var>(field, 0, setter);
+        return member<Var, Var>(field, 0, setter);
       }
 
       /**

simgear/nasal/cppbind/cppbind_test.cxx

@@ -23,6 +23,10 @@ struct Base
 
   std::string getString() const { return ""; }
   void setString(const std::string&) {}
+
+  std::string var;
+  const std::string& getVar() const { return var; }
+  void setVar(const std::string v) { var = v; }
 };
 struct Derived:
   public Base
@@ -135,7 +139,10 @@ int main(int argc, char* argv[])
 
   Ghost<BasePtr>::init("BasePtr")
     .method<&Base::member>("member")
-    .member("str", &Base::getString, &Base::setString);
+    .member("str", &Base::getString, &Base::setString)
+    .member("var_r", &Base::getVar)
+    .member("var_w", &Base::setVar)
+    .member("var", &Base::getVar, &Base::setVar);
   Ghost<DerivedPtr>::init("DerivedPtr")
     .bases<BasePtr>()
     .member("x", &Derived::getX, &Derived::setX)

simgear/nasal/cppbind/from_nasal.cxx

@@ -50,7 +50,7 @@ namespace nasal
   }
 
   //----------------------------------------------------------------------------
-  std::string from_nasal_helper(naContext c, naRef ref, std::string*)
+  std::string from_nasal_helper(naContext c, naRef ref, const std::string*)
   {
     naRef na_str = naStringValue(c, ref);
     return std::string(naStr_data(na_str), naStr_len(na_str));
@@ -63,7 +63,7 @@ namespace nasal
   }
 
   //----------------------------------------------------------------------------
-  Hash from_nasal_helper(naContext c, naRef ref, Hash*)
+  Hash from_nasal_helper(naContext c, naRef ref, const Hash*)
   {
     if( !naIsHash(ref) )
       throw bad_nasal_cast("Not a hash");
@@ -72,7 +72,7 @@ namespace nasal
   }
 
   //----------------------------------------------------------------------------
-  String from_nasal_helper(naContext c, naRef ref, String*)
+  String from_nasal_helper(naContext c, naRef ref, const String*)
   {
     if( !naIsString(ref) )
       throw bad_nasal_cast("Not a string");

simgear/nasal/cppbind/from_nasal_detail.hxx

@@ -71,27 +71,28 @@ namespace nasal
   /**
    * Simple pass through for unified handling also of naRef.
    */
-  inline naRef from_nasal_helper(naContext, naRef ref, naRef*) { return ref; }
+  inline naRef from_nasal_helper(naContext, naRef ref, const naRef*)
+  { return ref; }
 
   /**
    * Convert Nasal string to std::string
    */
-  std::string from_nasal_helper(naContext c, naRef ref, std::string*);
+  std::string from_nasal_helper(naContext c, naRef ref, const std::string*);
 
   /**
    * Convert a Nasal string to an SGPath
    */
-  SGPath from_nasal_helper(naContext c, naRef ref, SGPath*);
+  SGPath from_nasal_helper(naContext c, naRef ref, const SGPath*);
 
   /**
    * Convert a Nasal hash to a nasal::Hash
    */
-  Hash from_nasal_helper(naContext c, naRef ref, Hash*);
+  Hash from_nasal_helper(naContext c, naRef ref, const Hash*);
 
   /**
    * Convert a Nasal string to a nasal::String
    */
-  String from_nasal_helper(naContext c, naRef ref, String*);
+  String from_nasal_helper(naContext c, naRef ref, const String*);
 
   /**
    * Convert a Nasal number to a C++ numeric type
@@ -100,7 +101,7 @@ namespace nasal
   typename boost::enable_if< boost::is_arithmetic<T>,
                              T
                            >::type
-  from_nasal_helper(naContext c, naRef ref, T*)
+  from_nasal_helper(naContext c, naRef ref, const T*)
   {
     naRef num = naNumValue(ref);
     if( !naIsNum(num) )
@@ -113,7 +114,8 @@ namespace nasal
    * Convert a Nasal vector to a std::vector
    */
   template<class T>
-  std::vector<T> from_nasal_helper(naContext c, naRef ref, std::vector<T>*)
+  std::vector<T>
+  from_nasal_helper(naContext c, naRef ref, const std::vector<T>*)
   {
     if( !naIsVector(ref) )
       throw bad_nasal_cast("Not a vector");
@@ -132,7 +134,7 @@ namespace nasal
    */
   template<class Vec2>
   typename boost::enable_if<is_vec2<Vec2>, Vec2>::type
-  from_nasal_helper(naContext c, naRef ref, Vec2*)
+  from_nasal_helper(naContext c, naRef ref, const Vec2*)
   {
     std::vector<double> vec =
       from_nasal_helper(c, ref, static_cast<std::vector<double>*>(0));