Decorator Pattern presentation theory and examples

The Decorator Pattern is a structural design pattern used in object-oriented software development. Its main purpose is to extend the functionality of objects in a flexible and reusable manner. Instead of altering the object's code or using inheritance to create subclasses, the Decorator Pattern allows behavior to be added dynamically to individual objects without affecting other instances of the same class.

1. Decorator Design Pattern

2. Introduction Example Class Diagram Implementation Table of contents 01 02 03 04

3. Introduction Definition and Purpose 01

4. Definition The Decorator pattern is a structural design pattern that allows adding functionalities to objects dynamically and flexibly. It is achieved through composition instead of inheritance, enabling the extension of an object's capabilities without modifying its base code. In other words, the Decorator provides a way to add or remove responsibilities to existing objects incrementally and consistently.

5. Purpose Extend object functionalities dynamically. Enable flexible composition of behaviors. Comply with the Open/Closed Principle (OCP) by facilitating extension without modifying existing code.

6. Example Real-World Example 02

7. Real-World Example Original house Original house with a decorator (the additional floor is built on top of original structure) Applying an additional decorator on top of the existing decorator and modifying the house (now painting the house) Suppose that you own a single-story house, and you decide to build an additional floor on top of it. You may not want to change the architecture of the ground floor, but you may want to employ a new design for the newly added floor that can fit on top of the existing architecture.

8. Figure 1 Figure 2 Figure 3 The case shown in Figure 3 is optional. You can use an existing decorator object to enhance the behavior, or you can create a new decorator object and add the new behavior to it. In step 2, you could also directly paint the original house. You don’t need to start painting once the new floor is added. Real-World Example

9. Class Diagram Class Diagram and Solution Explorer 03

10. Implementation 04