Question

class X
{
protected:
    void protectedFunction() { cout << "I am protected" ; }
};

class Y : public X
{
public:
    using X::protectedFunction;
};

int main()
{
    Y y1;
    y1.protectedFunction();
}

This way I am able to expose one of the functions of the base class.

1. Doesn’t this violate the encapsulation principle?
2. Is there a specific reason as to why this is in standard?
3. Is there any uses of this, or is it going to be changed in the new standard?
4. Are there any open issues related to this in the standard?

Answer 1

Yes it does and that’s why protected has received a fair share of criticism.

Bjarne Stroustrup, the creator of C++, regrets this in his excellent book The Design and Evolution of C++:

One of my concerns about protected is
exactly that it makes it too easy to
use a common base the way one might
sloppily have used global data….In
retrospect, I think that protected is
a case where “good arguments” and
fashion overcame my better judgement
and my rules of thumb for accepting
new features.