Chapter 1, The Factory Pattern, will teach you how to use the Factory design pattern (Factory Method and Abstract Factory) to initialize objects, and also covers the benefits of using the Factory design pattern instead of direct object instantiation.
Chapter 2, The Builder Pattern, will teach you how to simplify the object creation process for cases typically composed of several related objects.
Chapter 3, Other Creational Patterns, will teach you how to handle other object creation situations with techniques such as creating a new object that is a full copy (hence, named clone) of an existing object, a technique offered by the Prototype pattern. You will also learn about the Singleton pattern.
Chapter 4, The Adapter Pattern, will teach you how to make your existing code compatible with a foreign interface (for example, an external library) with minimal changes.
Chapter 5, The Decorator Pattern, will teach you how to enhance the functionality of an object without using inheritance.
Chapter 6, The Bridge Pattern, will teach you how to externalize an object's implementation details from its class hierarchy to another object class hierarchy. This chapter encourages the idea of preferring composition over inheritance.
Chapter 7, The Facade Pattern, will teach you how to create a single entry point to hide the complexity of a system.
Chapter 8, Other Structural Patterns, will teach you the Flyweight, Model-View-Controller and Proxy patterns. With the Flyweight pattern, you will learn to reuse objects from an object pool to improve the memory usage and possibly the performance of your applications. The Model-View-Controller (MVC) pattern is used in application development (desktop, web) to improve maintainability by avoiding mixing the business logic with the user interface. And with the Proxy pattern, you provide a special object that acts as a surrogate or placeholder for another object to control access to it and reduce complexity and/or improve performance.
Chapter 9, The Chain of Responsibility Pattern, will teach another technique to improve the maintainability of your applications by avoiding mixing the business logic with the user interface.
Chapter 10, The Command Pattern, will teach you how to encapsulate operations (such as undo, copy, paste) as objects, to improve your application. Among the advantages of this technique, the object that invokes the command is decoupled from the object that performs it.
Chapter 11, The Observer Pattern, will teach you how to send a request to multiple receivers.
Chapter 12, The State Pattern, will teach you how to create a state machine to model a problem and the benefits of this technique.
Chapter 13, Other Behavioral Patterns, will teach you, among several other advanced programming techniques, how to create a simple language on top of Python, which can be used by domain experts without forcing them to learn how to
program in Python.
Chapter 14, The Observer Pattern in Reactive Programming, will teach you how to send a notification to the registered stakeholders of a stream of data (and events), whenever there is a state change.
Chapter 15, Microservices and Patterns for the Cloud, will teach you several system design patterns which are important with today's increasing adoption of Cloud-Native applications and microservices architectures. You will learn that you can split your application into functional and/or technical services that can be maintained and deployed more independantly, using microservices-oriented frameworks, containers, and other techniques. Since you rely more and more on remote services as part of an application (for example, an API), retry mechanisms are used in places where a call is possible to fail but, if retried more than once, it is more probable to succeed. As an addition to doing retries for fault-tolerance, you will learn how to use Circuit breakers, a technique to allow one subsystem to fail without destroying the entire system. In applications that rely heavily on accessing data from a data store, using the Cache-Aside pattern can improve the performance while reading data from the data store via caching. This pattern can be used for read and update operations of data to and from the data store. Last but not least, the chapter introduces the Throttling pattern, the concept where, based on a rate-limiting or alternative technique, you can control how users consume your API or your service and make sure the service does not get overwhelmed by one particular tenant.
