Initialize members at later point without using pointers possible? C-CodePudding

Say I have a class A, that consumes messages of a network. Class A has 2 members b and c of corresponding type B and C. The members can only be initialized with information, that comes from the network.

Is there a way to initialize the members at a later point, without having the members to be of type B* and C* (initialize with nullptr and set the wanted value later)?

I feel like in such a scenario the design has a flaw, but I am still asking myself what the best practice would be, as I am kind of sluggish when using pointers after reading Why should I use a pointer rather than the object itself? ?

CodePudding user response：

std::optional<T> is a "nullable" wrapper around a type T. It acts a bit like a pointer in syntax, but there is no dynamic allocation.

std::optional<int> bob;
if (bob) // is there anything in the box?
  std::cout << *bob; // print what is in the box.

You can do:

bob = 7; // Assign 7 to what is in `bob`, or construct with a 7.
bob.emplace(3); // construct the contents of `bob` with the value 3

When reading, you can do:

std::cout << bob.value_or(-1);

which either prints the value in bob, or (a T constructed from) -1 if there is nothing there.