|Posted by Rémy Mouëza||PermalinkReply|
I am experiencing polymorphism problems while implementing a visitor pattern.
I've got a visitor interface :
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 ?