Shared data class using std::shared_ptr

Question

I need a class that implements shared data semantics, and probably std::shared_ptr is a good place to start. I think a typical implementation of such class could use an private shared_ptr to the shared data, and then implement at least copy constructor and operator=.

Something like:

class SharedDataClass {

public:
  SharedDataClass(const SharedDataClass& other)
  {
    data_ = other.data_;
  };

  SharedDataClass& operator=(const SharedDataClass& other)
  {
    data_ = other.data_;
    return *this;
  }

private:
  std::shared_ptr<DataType> data_;
};

I'd like to ask if anyone has some criticism to offer on the above implementation. Is there any other member/operator that should be implemented for consistency?

std::shared_ptr<DataType> data takes care of all this for you. — Captain Giraffe
– Captain Giraffe, Commented Apr 19, 2016 at 8:30
Ok, so it seems that there is no particular warning flag to be raised as to the logic of the implementation, except for noting that default is all you really need in this case. I guess c++11 is succeeding in making things easier at last... — Emerald Weapon
– Emerald Weapon, Commented Apr 19, 2016 at 9:01

shrike · Accepted Answer · 2016-04-19 08:32:04Z

5

There is no need to implement a copy constructor or an assignment operator in this case. Let the compiler defines the trivial default ones for you, the shared_ptr will do the job you are expecting.

answered Apr 19, 2016 at 8:32

shrike

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1 Comment

Emerald Weapon Over a year ago

That's a good point, thanks. However this is more a way to obtain what I already have with less effort.

Emerald Weapon · Accepted Answer · 2016-04-19 09:19:14Z

1

I see one minor pitfall. Typically the default constructor should not be defaulted, as it will create a null data_ pointer. I think in general it is more desirable to have the default constructor to create a data_ pointer holding a default-constructed DataType object.

answered Apr 19, 2016 at 9:19

Emerald Weapon

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