Creation Design Patterns
Creational Design Patterns in Python
Creational design patterns provide various object creation mechanisms, which increase flexibility and reuse of existing code.
1. Singleton Pattern
The Singleton pattern ensures a class has only one instance and provides a global point of access to it.
1.1 Implementation using __new__
1.2 Implementation using a Decorator
1.3 Pros and Cons
- Pros:
- Ensures a single instance
- Global access point
- Lazy initialization
- Cons:
- Violates Single Responsibility Principle
- Can make unit testing difficult
- Can hide bad design
2. Factory Method Pattern
The Factory Method pattern provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created.
2.1 Example: Matrix Computation with Different Backends
2.2 Benefits of Factory Method
- Provides flexibility in object creation
- Promotes loose coupling
- Adheres to the Open/Closed Principle
- Simplifies adding new types of objects
3. Abstract Factory Pattern
The Abstract Factory pattern provides an interface for creating families of related or dependent objects without specifying their concrete classes.
3.1 Example: Cross-platform UI Components
3.2 Benefits of Abstract Factory
- Ensures compatibility between created objects
- Isolates concrete classes
- Simplifies exchanging product families
- Promotes consistency among products
4. Builder Pattern
The Builder pattern separates the construction of a complex object from its representation, allowing the same construction process to create different representations.
4.1 Example: Custom Computer Builder
4.2 Benefits of Builder
- Allows step-by-step creation of complex objects
- Can use the same construction code for different representations
- Isolates complex construction code from business logic
Conclusion
Creational design patterns solve problems related to object creation in software design. They provide flexibility, improve code reusability, and help manage complexity in object-oriented systems. Each pattern has its specific use cases, and understanding them allows developers to choose the right tool for the job when designing software systems.