Friend Class of child try to access protected function of Parent

Question

I've got a Parent Class and a Child Class. The Parent have a protected function called setId(int id). Now I want to make the setId function acessable by friend class of Child (lets call it Friend). Is this possible or do I have to reimplement the setId function inside the Child class and use the protected setId function of parent?

I've tried this with VS-Compiler and it works.

I use gcc and get "error: ‘void Parent::setId(int)’ is protected"

Class Parent

class Parent
{
public:
    Parent(){}

protected:
    void setId(int id){m_id=i}

    int m_id;
};

Class Child

#include "Parent.h"

class Child
        : public Parent
{
    friend class FriendClass;
public:
    Child(){}
};

Class Friend

#include "Child.h"

class FriendClass
{
public:
    FriendClass(){
      Child c;
      c.setId(1);
    }
};

Instead of describing the code, please *show* it to us. Preferably in the form of a [Minimal, Complete, and Verifiable Example](http://stackoverflow.com/help/mcve). — Some programmer dude, Jun 12 '18 at 06:00
[No repro](https://ideone.com/xKeiHu). Please post a [mcve]. — n. m. could be an AI, Jun 12 '18 at 06:12

score 1 · Accepted Answer · answered Jun 12 '18 at 08:27

Common wisdom holds that the right way is to upgrade access in Child:

class Child: public Parent {
public:
    void setId(int id) override { Parent::setId(id); } // public for Friend
};

The usual rationale is that this is brief and expresses clearly and precisely what's being made public, without publishing any other internals.

Friend Class of child try to access protected function of Parent

1 Answers1