Class variables: public access read-only, but private access read/write

Question

Whoopee, not working on that socket library for the moment. I\'m trying to educate myself a little more in C++.

With classes, is there a way to make a variable read-

Answer 1

There is a way to do it with a member variable, but it is probably not the advisable way of doing it.

Have a private member that is writable, and a const reference public member variable that aliases a member of its own class.

class Foo
{
  private:
      Bar private_bar;

  public:
      const Bar& readonly_bar; // must appear after private_bar
                              // in the class definition

  Foo() :
       readonly_bar( private_bar )
  {
  }
};

That will give you what you want.

void Foo::someNonConstmethod()
{
    private_bar.modifyTo( value );
}

void freeMethod()
{
    readonly_bar.getSomeAttribute();
}

What you can do, and what you should do are different matters. I'm not sure the method I just outlined is popular and would pass many code reviews. It also unnecessarily increases sizeof(Foo) (albeit by a small amount) whereas a simple accessor "getter" would not, and can be inlined, so it won't generate more code either.