#include "eyebrow.h"
class Face {
    public:
        enum Expression {NEUTRAL, JOY, ANGER};
        void setExpression(Expression);
    private:
         Eyebrow left_eyebrow;
}

#include "face.h"
#include "eyebrow.h"

void Face::setExpression(Expression e) {
     left_eyebrow.setExpression(e);
}

#include "face.h"

class Eyebrow {
    public:
         void setExpression(Face::Expression);
};

add_executable(Main main.cpp face.cpp eyebrow.cpp)

#include "face.h"

class Face;
class Eyebrow {
    public:
         void setExpression(Face::Expression);
};