Programming Design Patterns

Separates the construction of a complex object from its representation, allowing the same process to create different representations.

Creates new objects by copying an existing object (the prototype), avoiding costly instantiation.

Allows incompatible interfaces to work together by converting the interface of one class into another interface clients expect.

Attaches new responsibilities to an object dynamically. Provides a flexible alternative to subclassing for extending functionality.

Provides a simplified interface to a complex system of classes, making it easier to use.

Provides a surrogate or placeholder for another object to control access to it.

Defines a family of algorithms, encapsulates each one, and makes them interchangeable.

Encapsulates a request as an object, thereby allowing for parameterization of clients with different requests.

Provides an interface for creating families of related or dependent objects without specifying their concrete classes.

Separates the construction of a complex object from its representation, allowing the same process to create different representations.

Defines an interface for creating an object, but lets subclasses decide which class to instantiate. Subclasses defer instantiation.

Provides a unified interface to a set of interfaces in a subsystem, making the subsystem easier to use.

Provides a surrogate or placeholder for another object to control access to it.

Attaches new responsibilities to an object dynamically. Provides a flexible alternative to subclassing for extending functionality.

Converts the interface of a class into another interface clients expect. It lets classes work together that couldn't otherwise because of incompatible interfaces.

Defines the skeleton of an algorithm in an operation, deferring some steps to subclasses. It lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure.

Encapsulates a request as an object, thereby allowing for parameterization of clients with different requests, queuing requests, or logging operations.

Provides a way to access the elements of an aggregate object sequentially without exposing its underlying representation.

Defines a family of algorithms, encapsulates each one, and makes them interchangeable. It lets the algorithm vary independently from clients that use it.

Allows a client to visit elements of an object structure without exposing its concrete classes. It defines a new operation to be performed on the elements of an object structure without changing the element classes.

Encapsulates how a set of objects interact. It promotes loose coupling by keeping objects from referring to each other explicitly.

Provides a way to produce objects in a class hierarchy when their exact type isn't known at compile time. It acts as a virtual constructor.

Ensures a class only has one instance, and provides a global point of access to it.

Allows an object to alter its behavior when its internal state changes. The object will appear to change its class.

Provides a way to undo/redo operations by restoring an object to its previous state. It captures and externalizes an object's internal state without violating encapsulation.

Defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.