Prototype Design Pattern

When do we need it?

Let's take an example to understand this. Say, I am going to create an e-commerce website which sells only movies and books. I would need to create objects for each movies and books and object creation may include costly operations. What would be the best approach in such a scenario?

Prototype Design Pattern can be helpful in such scenarios. The concept behind this design pattern is we copy the existing object instead of creating a new instance, which may include costly operations everytime. The existing object acts as a prototype and contains the state of the object.

For the above-mentioned example, we created two classes Book.java and Movie.java and inherited the Item.java class.

These two classes will act as prototypes for us.

Then we create a Registry which will basically clone the prototype everytime we will need a new instance.

Pitfalls

• Most of the time it needs to be used with other patterns.
  • Registry.
• Shallow vs Deep Copy.

Summary

• It gurantees an unique instance everytime.
• Often refactored in.
• Can help in performance issues.