Arduino: Inheritance and arrays of pointer subclasses - c++

Question

This is problem #2 from this previous question:
Inheritance in Arduino Code
Building off of Steven's answer, I do need the array that holds the pointers to persist outside of its scope, which is resulting in some weird behavior.
This is my "Board" class I have so far, that contains multiple child elements:
Board.h:
#ifndef Board_h
#define Board_h
#include <StandardCplusplus.h>
#include <serstream>
#include <string>
#include <vector>
#include <iterator>
#include "Arduino.h"
#include "Marble.h"
#include "Wall.h"
class Board
{
public:
Board();
void draw(double* matrix);
private:
Marble marble;
//std::vector<Actor> children;
Actor* children[2];
};
#endif
Board.cpp:
#include "Arduino.h"
#include "Board.h"
#include <math.h>
#include <iterator>
#include <vector>
Board::Board()
{
}
void Board::create(double* _matrix, int _cols, int _rows) {
Marble *marble = new Marble();
Wall wall;
children[0] = marble;
//children.push_back(marble);
//children.push_back(wall);
}
void Board::draw(double* matrix) {
Serial.println("board draw");
children[0]->speak();
}
In my "loop" function I am calling
board.draw(matrix);
which results in some nutty Serial code being written out.
Clearly I am not understanding the ins and outs of pointers in arrays in classes here.

Answer 1

You need to make Actor::speak virtual, the compiler uses dynamic binding for virtual methods.
class Actor
{
public:
Actor();
virtual void speak(); // virtual
private:
};