Reassignment of a reference

Question

Suppose I have a class

class Foo
{
  public:
    ~Foo() { delete &_bar; }
    void SetBar(const Bar& bar)
    {
      _bar = bar;
    }
    const Bar& GetBar() { return _bar; }
  private:
    Bar& _bar;
}

And my usage of this class is as follows (assume Bar has a working copy constructor)

Foo f;
f.SetBar(*(new Bar));
const Bar* bar = &(f.GetBar());
f.SetBar(*(new Bar(bar)));
delete bar;

I have a situation similar to this (in code I didn't write) and when I debug at a breakpoint set on the "delete bar;" line, I see that

&f._bar == bar

My question is this: Why do &f._bar and bar point to the same block of memory, and if I leave out the "delete bar;", what are the consequences, from a memory management standpoint?

Many thanks!

Answer 1

The code you posted wouldn't compile, because references cannot be default constructed. Also, you seem to think you are reseating a reference, which you are not (see here). Instead, you are just copying objects over whatever _bar was referencing, so the value of:

&(f.GetBar())

never changes. You shouldn't delete _bar because you never owned it (or even really knew it was dynamically allocated) to begin with. That should be the responsibility of whoever "newed" it.

Answer 2

References cannot be "reseated", setBar() just copies the contents of bar to the object referenced by _bar.

If you need such a functionality use pointers instead. Also your usage example would be much simpler if you were just using pointers.