What is the advantage of passing by reference to shared_ptr over passing by reference directly

Question

class myMem{};

class Test{
public:
  initMem1(myMem& mInput){/*initialize _mem1*/}
  initMem2(shared_ptr<myMem> &pmInput){/*initialize _mem2*/}

  myMem _mem1;
  shared_ptr<myMem> _mem2;
};

Test myTest;
myTest()

So, in the code above, members belong to a class. One member is a value type and another member is a shared_ptr type. Which way is better for a class member? Moreover, I also have the functions to initialize the members. Which way is better?

In general what is the advantage of passing by reference to shared_ptr over passing by reference directly?

Answer 1

The only reason a function should accept a std::shared_ptr as a argument is if it may need to share or modify the ownership of the resource. If not, don't pass a std::shared_ptr.

If the function will definitely need to take shared ownership then it should accept a std::shared_ptr by value. Only accept a std::shared_ptr& if the function may or may not take shared ownership.

If the function does not modify ownership then pass a reference to the resource, not a std::shared_ptr.

See: CppCoreGuidelines: F.7, R.30, R.34, R.35