Design Patterns in Software Design

Study Notes

Design patterns are reusable solutions to common problems that arise during software design.

Deal with object creation mechanisms
Focus on the creation of objects and how they are structured
Examples:
- Factory Pattern
- Singleton Pattern
- Abstract Factory Pattern
- Builder Pattern

Focus on the interactions between objects
Define how objects communicate with each other
Examples:
- Observer Pattern
- Strategy Pattern
- Template Method Pattern
- Iterator Pattern

A creational pattern that provides a way to create objects without specifying the exact class of object
Uses a factory method to create objects
Advantages:
- Encapsulates object creation
- Reduces coupling between objects
- Increases flexibility and scalability

Focus on the composition of objects and how they are structured
Define how objects are composed to form larger structures
Examples:
- Adapter Pattern
- Bridge Pattern
- Composite Pattern
- Decorator Pattern

A creational pattern that ensures only one instance of a class is created
Provides a global point of access to the instance
Advantages:
- Ensures only one instance is created
- Provides a global point of access
- Reduces memory usage
- Improves performance

Deal with object creation mechanisms and structure
Examples:
- Factory Pattern: provides a way to create objects without specifying the exact class
- Singleton Pattern: ensures only one instance of a class is created
- Abstract Factory Pattern: provides a way to create families of related objects
- Builder Pattern: separates the construction of complex objects from their representation

Focus on interactions between objects and how they communicate with each other
Examples:
- Observer Pattern: defines a one-to-many dependency between objects
- Strategy Pattern: defines a family of algorithms and encapsulates each one
- Template Method Pattern: provides a skeleton for algorithms and allows subclasses to customize it
- Iterator Pattern: provides a way to access the elements of an aggregate object without exposing its underlying representation

Creational pattern that encapsulates object creation and reduces coupling between objects
Uses a factory method to create objects without specifying the exact class
Advantages:
- Encapsulates object creation
- Reduces coupling between objects
- Increases flexibility and scalability

Focus on the composition of objects and how they are structured to form larger structures
Examples:
- Adapter Pattern: converts the interface of a class to match another interface
- Bridge Pattern: separates an object's abstraction from its implementation
- Composite Pattern: represents a group of objects as a single object
- Decorator Pattern: adds additional responsibilities to an object without affecting other objects