Returning const reference from a member get method

Question

typedef vector<int> intvec;

class MyClass
{
    intvec m_member;
public:
    const intvec& GetVec();
};

const intvec& MyClass::GetVec()
{
    return m_member;
}

int main(int argc, char *argv[])
{
    MyClass myClassObj;

    myClassObj.GetVec().push_back(11); //This doesn't work with const reference
    myClassObj.GetVec().push_back(22); //This doesn't work with const reference

    for(intvec::const_iterator iter = myClassObj.GetVec().begin(); iter != myClassObj.GetVec().end(); ++iter)
    {
        cout << *iter << ", " ;
    }

    cout << endl;

    system("PAUSE");
    return EXIT_SUCCESS;
}

If the return type of GetVec() is non const reference then myClassObj.GetVec().push_back(11); works, but for const reference return this doesn't work (compilation error). I understand that if the GetVec() method itself was const i.e. const intvec& GetVec() const;, then myClassObj.GetVec().push_back(11); wouldn't work because that would mean modifying the "this" pointer.

Answer 1

You can overload the function on it's const qualification:

const intvec& GetVec() const;    // Can access, but not modify, a const object
intvec& GetVec();                // Can access or modify a non-const object

Or you could just make the data member public and have exactly the same restrictions. There's little point in accessor functions unless they're used to restrict access or maintain class invariants, which these don't.