An example introduction to 'Appearance Pattern' for learning Python design patterns

In the Java framework, the difference between design patterns and architectural patterns is that design patterns define abstract solutions to common problems in software design, focusing on the interaction between classes and objects, such as factory patterns. Architectural patterns define the relationship between system structures and modules, focusing on the organization and interaction of system components, such as layered architecture.

The decorator pattern is a structural design pattern that allows dynamic addition of object functionality without modifying the original class. It is implemented through the collaboration of abstract components, concrete components, abstract decorators and concrete decorators, and can flexibly expand class functions to meet changing needs. In this example, milk and mocha decorators are added to Espresso for a total price of $2.29, demonstrating the power of the decorator pattern in dynamically modifying the behavior of objects.

Design patterns solve code maintenance challenges by providing reusable and extensible solutions: Observer Pattern: Allows objects to subscribe to events and receive notifications when they occur. Factory Pattern: Provides a centralized way to create objects without relying on concrete classes. Singleton pattern: ensures that a class has only one instance, which is used to create globally accessible objects.

1. Factory pattern: Separate object creation and business logic, and create objects of specified types through factory classes. 2. Observer pattern: allows subject objects to notify observer objects of their state changes, achieving loose coupling and observer pattern.

The Adapter pattern is a structural design pattern that allows incompatible objects to work together. It converts one interface into another so that the objects can interact smoothly. The object adapter implements the adapter pattern by creating an adapter object containing the adapted object and implementing the target interface. In a practical case, through the adapter mode, the client (such as MediaPlayer) can play advanced format media (such as VLC), although it itself only supports ordinary media formats (such as MP3).

TDD is used to write high-quality PHP code. The steps include: writing test cases, describing the expected functionality and making them fail. Write code so that only the test cases pass without excessive optimization or detailed design. After the test cases pass, optimize and refactor the code to improve readability, maintainability, and scalability.

The Guice framework applies a number of design patterns, including: Singleton pattern: ensuring that a class has only one instance through the @Singleton annotation. Factory method pattern: Create a factory method through the @Provides annotation and obtain the object instance during dependency injection. Strategy mode: Encapsulate the algorithm into different strategy classes and specify the specific strategy through the @Named annotation.

The advantages of using design patterns in Java frameworks include: enhanced code readability, maintainability, and scalability. Disadvantages include complexity, performance overhead, and steep learning curve due to overuse. Practical case: Proxy mode is used to lazy load objects. Use design patterns wisely to take advantage of their advantages and minimize their disadvantages.