Catalog of Design Patterns

1. Abstract Factory - provides an interface for creating families of related or dependent object without specifying their concrete classes.
2. Adapter - converts the interface of a class into another interface clients expect. Adapter lets classes work together that couldn't otherwise because of incompatible interfaces.
3. Bridge - decouples an abstraction from its implementation so that the two can vary independently.
4. Chain of Responsibility - Avoids coupling the sender of a request to its receiver by giving more than one object a change to handle the request. Chain the receiving objects and pass the request along the chain until an object handles it. {Could this be use in AI?}
5. Command - encapsulates a request as an object, thereby letting me parameterize clients with different requests, queue or log requests, and support undoable operations.
6. Composite - composes objects into tree structures to represent part-whole hierarchies. Composite lets clients treat individual objects and compositions of objects uniformly.
7. Decorator - attach additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality.
8. Facade - provides a unified interface to a set of interfaces in a subsystem. Facade defines a higher-level interface that makes the subsystem easier to use.
9. Factory Method - defines a interface for creating an object, but lets subclasses decide which class to instantiate. Factory Method lets a class defer instantiation to subclasses.
10. Flyweight - is used to support sharing a large number of fine-grained object efficiently.
11. Interpreter - given a language, define a represention for its grammar along with interpreter that uses the representation to interpret sentences in the language.
12. Iterator - provides a way to access the elements of an aggregate object sequentially without exposing its underlying representation.
13. Mediator - defines an object that encapsulates how a set of objects interact.
    

{more to be done}

Describing Design Patterns

Pattern Name and Classification

Intent

Also Known As

Motivation

Applicability

Structure

Participants

Collaborations

Consequences

Implementation

Sample Code

Known Uses

Related Patterns

Model/View/Controller (MVC)

The Model/View/Controller is used in Smalltalk and is an example of an Observer design pattern.

It also contains the Composite design pattern.

Four Essential Elements to a Design Pattern

1. Pattern Name - the handle used to describe a design problem, its solutions, and consequenes. Allows design at a higher level of abstraction.
2. Problem - describes when to apply the pattern. Describes the problem and its context.
3. Solution - describes the elements that make up a design, their relationships, responsibilities, and collaborations. A template that can be applied in many different situations. Provides an abstract description of a design problem and how a general arrangement of elements (classes and object) solves it.
4. Consequences - the results and trade-offs of applying the pattern. Critical in evaluating design alternatives and understanding the costs and benefits of applying the pattern.