Design Patterns

Creational patterns Factory Method: Define an interface for creating a single object, but let subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses. Abstract Factory: Provide an interface for creating families of related or dependent objects without specifying their concrete classes. Builder: Separate the construction of a complex object from its representation, allowing the same construction process to create various representations. Prototype: Specify the kinds of objects to create using a prototypical instance, and create new objects from the ‘skeleton’ of an existing object, thus boosting performance and keeping memory footprints to a minimum....

The Visitor pattern is a behavioral pattern that separates an algorithm from an object structure on which it operates. The pattern allows you to add new operations or algorithms to an object structure without modifying the structure itself. The pattern achieves this by defining a separate object called a visitor, which can traverse an object structure and apply a specific operation to each element of the structure. The main idea behind the Visitor pattern is to provide a way to separate the concerns of an algorithm from the object structure it operates on....

The Template Method pattern is a behavioral pattern that defines the basic steps of an algorithm and allows subclasses to override some of the steps without changing the algorithm’s structure. The pattern defines a skeleton of an algorithm in a base class and allows subclasses to implement the details of the algorithm in their own way. The main idea behind the Template Method pattern is to provide a way to define a common algorithm structure that can be reused across different subclasses, while still allowing the subclasses to customize some parts of the algorithm’s behavior....

The Strategy pattern is a behavioral pattern that allows you to define a family of algorithms, encapsulate each one as an object, and make them interchangeable. The pattern allows you to vary the behavior of an object by selecting the appropriate algorithm at runtime. The main idea behind the Strategy pattern is to provide a way to change an object’s behavior without changing its implementation. Instead of implementing a single algorithm directly in the object, the Strategy pattern defines a set of algorithms as separate objects and allows the object to select the appropriate algorithm at runtime....

The State pattern is a behavioral pattern that allows an object to alter its behavior when its internal state changes. The pattern encapsulates state-dependent behavior into separate classes, and the object’s behavior changes at runtime by switching between different state objects. The main idea behind the State pattern is to provide a way to change an object’s behavior without changing its class. Instead of using conditional statements to determine the behavior of an object based on its state, the State pattern uses a set of state classes that encapsulate the behavior and a context object that delegates to the current state....