In Chapter 3, Encapsulation of Data with Properties, we created a class to represent a mutable 3D vector named MutableVector3D and a class to represent an immutable version of a 3D vector named ImmutableVector3D.
Both versions were capable of working with 3D vectors with Float values for x, y, and z. We now realize that we also have to work with 3D vectors with Double values for x, y, and z in both classes. We definitely don't want to create two new classes, such as MutableDoubleVector3D and ImmutableDoubleVector3D. We can take advantage of generics to create two classes capable of working with elements of any floating point type supported in Swift—that is, either Float, Float80, or Double.
We want to create the following two classes:
MutableVector3D<T>ImmutableVector3D<T>
It seems to be a pretty simple task. We just have to replace Float with the generic type parameter, T, and change the class declaration to include the generic type...
