Hands-On Design Patterns with Kotlin

Starting from a prototype

The whole idea of a prototype is to be able to clone an object easily. There are a number of reasons you may want to do this:

• Creating your object is very expensive. You need to fetch it from the database.
• You create objects that are similar but different from one another, and you don't want to repeat similar parts over and over again.

There are also more advanced reasons to use this pattern. JavaScript language, for example, uses prototypes to implement inheritance-like behavior without having classes.

Luckily, Kotlin fixes the broken Java clone() method. For data classes, there's the copy() method, which takes an existing data class, and creates a new copy of it, optionally changing some of its attributes in ...