What is an optional reference?
orx is an optional reference. It means that it either represents a reference (bound to another object, like all references), or an empty optional (so bound to nothing).
Where is optional used?
Use Optional Everywhere
- design your classes to avoid optionality wherever feasibly possible.
- in all remaining cases, the default should be to use Optional instead of null.
- possibly make exceptions for: local variables. return values and arguments to private methods.
What is optional object used for?
Optional object is used to represent null with absent value. This class has various utility methods to facilitate code to handle values as ‘available’ or ‘not available’ instead of checking null values.
What is STD optional?
The class template std::optional manages an optional contained value, i.e. a value that may or may not be present. A common use case for optional is the return value of a function that may fail.
What happens if OPT _ B is a reference to other _ obj?
This is true for all T, including T& : If opt_b is a reference to my_obj, then opt_a will also be a reference to my_obj, even it was a reference to other_obj before. So the copy assignment operator does a rebind operation.
What is optional object used for in Java?
Optional is a container object used to contain not-null objects. Optional object is used to represent null with absent value.
When to use STD : : optional < T & >?
Here we want to either avoid a copy, or modify an argument in-place. If we want to have optional arguments, a std::optional is a solution. However, simply overloading the function works as well. Again, we want to avoid a copy.
Why is writing ref = OBJ not an assignment?
Sure, writing ref = obj compiles, but it is not an assignment. It only works because every operation done on a reference is done on the object it refers to. Now as I said before, when we have a nullable reference we can’t do that, because then we would have no syntax to check for nullability.