Mutability is very important in object-oriented programming. In fact, whenever we expose mutable properties, we create a class that will generate mutable instances. However, sometimes a mutable object can become a problem, and in certain situations, we want to avoid the objects to change their state. For example, when we work with concurrent code, an object that cannot change its state solves many concurrency problems and avoids potential bugs.
For example, we can create an immutable version of the previous
MutableVector3D class to represent an immutable 3D vector. The new
ImmutableVector3D class has three immutable instance properties declared with the
let keyword instead of the previously used
y, and ...