add missing const_SlotProxy ctor

Author: kevinushey

ChangeLog

@@ -1,3 +1,8 @@
+2014-03-03  Kevin Ushey <kevinushey@gmail.com>
+
+        * inst/include/Rcpp/proxy/SlotProxy.h: Add missing const_SlotProxy ctor
+        definition
+
 2014-02-24  Kevin Ushey  <kevinushey@gmail.com>
 
         * R/Rcpp.package.skeleton.R: make sure we add loadModule

inst/include/Rcpp/proxy/SlotProxy.h

@@ -63,9 +63,12 @@ class SlotProxyPolicy {
 
     class const_SlotProxy : public GenericProxy<const_SlotProxy> {
     public:
-        const_SlotProxy( const CLASS& v, const std::string& name) ;
-        const_SlotProxy& operator=(const const_SlotProxy& rhs) ;
-              
+        const_SlotProxy( const CLASS& v, const std::string& name) : parent(v), slot_name(Rf_install(name.c_str())) {
+            if( !R_has_slot( v, slot_name) ){
+                throw no_such_slot() ; 
+            }  
+        }
+        
         template <typename T> operator T() const {
           return as<T>( get() );
         }