notes for design patterns and rss feed

20251223215636-design_patterns_notes.org

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 *WIP*
 
-* Design patterns. What are they?
+* Summary of the major patterns:
 
+** The Strategy Pattern
+Strategy is a behavioral design pattern that lets you define a family of algorithms, put each of them into a separate class, and make their objects interchangeable.
+
+[[./assets/design-patterns/structure-pattern.png]]
+
+
+
+** Observer pattern
+Observer is a behavioral design pattern that lets you define a subscription mechanism to notify multiple objects about any events that happen to the object they’re observing.
+
+[[./assets/design-patterns/observer-pattern.png]]
+
+
+** Decorator pattern
+
+Decorator is a structural design pattern that lets you attach new behaviors to objects by placing these objects inside special wrapper objects that contain the behaviors.
+
+The problem:
+
+[[./assets/design-patterns/decorator-problem.png]]
+
+[[./assets/design-patterns/decorator-pattern.png]]
+
+
+** Factory Pattern
+Factory Method is a creational design pattern that provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created.
+
+[[./assets/design-patterns/factory-pattern.png]]
+
+
+** Singleton Pattern
+Singleton is a creational design pattern that lets you ensure that a class has only one instance, while providing a global access point to this instance.
+
+[[./assets/design-patterns/singleton-pattern.png]]
+
+
+** Command Pattern
+Command is a behavioral design pattern that turns a request into a stand-alone object that contains all information about the request. This transformation lets you pass requests as a method arguments, delay or queue a request’s execution, and support undoable operations.
+
+[[./assets/design-patterns/command-pattern.png]]
+
+
+** Adapter Pattern
+Adapter is a structural design pattern that allows objects with incompatible interfaces to collaborate.
+
+[[./assets/design-patterns/adapter-pattern.png]]
+
+Another approach:
+
+[[./assets/design-patterns/adapter-pattern-2.png]]
+
+** Facade Pattern
+Facade is a structural design pattern that provides a simplified interface to a library, a framework, or any other complex set of classes.
+
+[[./assets/design-patterns/facade-pattern.png]]
+
+
+** Template Method Pattern
+Template Method is a behavioral design pattern that defines the skeleton of an algorithm in the superclass but lets subclasses override specific steps of the algorithm without changing its structure.
+
+[[./assets/design-patterns/template-method-pattern.png]]
+
+** Iterator and Composite Pattern
+Iterator is a behavioral design pattern that lets you traverse elements of a collection without exposing its underlying representation (list, stack, tree, etc.).
+
+[[./assets/design-patterns/iterator-pattern.png]]
+
+Composite is a structural design pattern that lets you compose objects into tree structures and then work with these structures as if they were individual objects.
+
+[[./assets/design-patterns/composite-pattern.png]]
+
+** State Pattern
+State is a behavioral design pattern that lets an object alter its behavior when its internal state changes. It appears as if the object changed its class.
+
+[[./assets/design-patterns/state-pattern.png]]
+
+** Proxy Pattern
+Proxy is a structural design pattern that lets you provide a substitute or placeholder for another object. A proxy controls access to the original object, allowing you to perform something either before or after the request gets through to the original object.
+
+[[./assets/design-patterns/proxy-pattern.png]]
+
+* Design patterns. What are they?
 
 They are reusable solutions to common problems in software design. They help to make code more flexible, maintainable, and scalable.