Design Patterns are proven, reusable solutions to commonly occurring programming problems. They are not specific pieces of code but are best practices or guidelines that provide a structure to solve recurring issues in software design.
Example
Imagine you have a coffee machine that only makes coffee. Now, you want to make different types of tea as well.
You could use the Factory Method Pattern if you know about design patterns. This allows you to define a factory method for creating coffee and tea while adhering to the same structure.
Where design patterns might fall short
Suppose you now want the machine to prepare soup, cold drinks, and fruit salad as well. Here, a simple factory method might not be sufficient. You may need an Abstract Factory Pattern or even a complete redesign of the machine's logic.
Main Categories of Design Patterns:
Creational Patterns (e.g., Singleton, Factory Method)
Structural Patterns (e.g., Adapter, Decorator)
Behavioral Patterns (e.g., Observer, Strategy)
They are critical for making software scalable, maintainable, and reusable.
1. Creational Patterns
Focus: Object creation.
Purpose: Ensure objects are created in a controlled and efficient way, supporting scalability and flexibility.
2. Structural Patterns
Focus: Class and object composition.
Purpose: Define how classes and objects interact and form larger structures.
3. Behavioral Patterns
Focus: Communication and interaction between objects, i.e. methods
Purpose: Manage algorithms, relationships, and responsibilities between objects.