accessing a protected member of a base class in another subclass

user_404734 0
Viewed 27653

Why does this compile:

class FooBase
{
protected:
    void fooBase(void);
};

class Foo : public FooBase
{
public:
    void foo(Foo& fooBar)
    {
        fooBar.fooBase();
    }
};

but this does not?

class FooBase
{
protected:
    void fooBase(void);
};

class Foo : public FooBase
{
public:
    void foo(FooBase& fooBar)
    {
        fooBar.fooBase();
    }
};

On the one hand C++ grants access to private/protected members for all instances of that class, but on the other hand it does not grant access to protected members of a base class for all instances of a subclass. This looks rather inconsistent to me.

I have tested compiling with VC++ and with ideone.com and both compile the first but not the second code snippet.

protected encapsulation inheritance c++
8 Answers

You can work around without a friend like so...

class FooBase
{
protected:
    void fooBase(void);
    static void fooBase(FooBase *pFooBase) { pFooBase->fooBase(); }
};

This avoids having to add derived types to the base class. Which seems a bit circular.

user_40203800
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