Use of operator()() without parentheses?

user_2369597 0
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The following code is a dumbed down version of a wrapper around an object. I would like to be able to access the underlying Object seamlessly, that is, without the need for parentheses, as the comments describe:

struct A
{
  void Func() {}
};

template <typename Object>
struct ObjectWrapper
{
  ObjectWrapper(Object& o) : object_(&o) {}

  operator Object& () { return *object_; }
  Object& operator ()() { return *object_; }

  Object* object_;
};


int main()
{
  A a;
  ObjectWrapper<A> obj(a);

  //
  // Trying to call Func() on the A object that 'obj' wraps...
  //

  obj.operator A& ().Func(); // Messy

  obj().Func(); // Better but still has parentheses

  // I really want to be able to say this:
  // obj.Func()
  // ...but cannot see how!
}

Can anyone please suggest a way of doing this?

templates c++
1 Answers

I think you need overload operator -> and/or * (this is how smart pointers are done):

template <typename Object>
struct ObjectWrapper {
    ObjectWrapper(Object& o)
        : object_(&o)
    {
        LOG();
    }

    Object* operator->() const
    {
        LOG();
        return object_;
    }

    Object& operator*() const
    {
        LOG();
        return *object_;
    }

    Object* object_;
};

int main()
{
    A a;
    ObjectWrapper<A> obj { a };
    obj->Func();
    (*obj).Func();
}

https://godbolt.org/z/ErEbxWE4P

user_13874380
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