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April 03, 2007
Runtime Polymorphism Issue
I am experiencing polymorphism problems while implementing a visitor pattern. 
I've got a visitor interface : 
       interface Visitor
   {
       char [] visit ( T node ); 
   }
and several subclasses of class Node. 
Node has got a "char [] accept ( Visitor visitor )" method, that I override in its subclasses:
   override char [] accept ( Visitor visitor )
   {
       return visitor.visit ( this );
   }
I am trying to generate some C code with a VisitorC object that implements Visitor: 
   char [] content = "int main ( int * argc, char ** argv );" ; 
   auto analysis = analyse ( content ); // Of type FunctionType ( char [] T = "Function" ): Node casted to Node.  
   auto visitor = new VisitorC ;

   cout << typeid ( typeof ( analysis )) << \n ; // Prints compile time type: Node. 
   cout << "code gen: " << analysis.accept ( visitor ) << \n ;
( cout is an instance of a class with a templated opShl method that uses writef )
I was expecting to get the visit ( FunctionType ) method called, but the overload resolution is made according to the compile time type, not the runtime type and the Node.visite () method is called instead. 

I wanted to know if this was a feature, or if I missed something in order to get the behaviour I want. 
Has anyone  a clue about this ?
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