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design pattern
subject			fact

design pattern	has definition A pattern useful for the design of software
	has antipatterns zero or more antipatterns - solutions that are inferior or do not work in this context with the reason for their rejection
	has context a context
	has forces one or more forces
	has name
	has problem a sentence or two explaining the main difficulty being tackled
	has references one or more references which indicate who developed or inspired a pattern
	has related patterns zero or more related design patterns
	is a subtopic of 6.1 - Introduction to Patterns
	is a kind of pattern
	should be illustrated using a simple diagram
	should be written using a narrative writing style
pattern	should be as general as possible
	should be described in an easy-to-understand form so that people can determine when and how to use it
	should contain a solution that has been proven to effectively solve the problem in the indicated context

Kinds of design pattern :

• abstraction-occurrence (10 facts) - A pattern in which two classes are related by an association, and one of the classes represents an abstraction of the other
• adapter (9 facts) - A pattern found in class diagrams in which you are able to reuse an 'adaptee' class by providing a class, (the adapter) that delegates to the adaptee
• antipattern (4 facts) - A solution to a design problem that is inferior or does not work in this context
• composite (3 facts) - A specialization of the general hierarchy pattern, that uses an aggregation instead of an ordinary association
• delegation (9 facts) - A pattern in which one procedure does nothing more than call another in a neighbouring class; this reduces total coupling in the system
• facade (8 facts) - A pattern in which you create a class that provides a simplified interface to a package
• general hierarchy (9 facts) - A pattern in which two classes are related both by a generalization and by a one to many association, such that the generated graph of instances forms a hierarchy
• immutable (8 facts) - A pattern in which the instances of a class cannot change state after creation
• observer (10 facts) - A pattern found in class diagrams in which instances of one class are informed of changes to instances of a second class
• player-role (9 facts) - A pattern in found in class diagrams in which one class (the player) has several associated role classes. Instances of the role classes can change over the lifetime of a player
• proxy (10 facts) - A pattern found in which a lightweight object stands in place of a heavyweight object that has the same interface. It transparently loads the heavyweight object when needed
• read-only interface (8 facts) - A pattern in which an interface is used to restrict which classes have privileges to call update methods of a class
• related pattern (4 facts) - A pattern that are similar to another pattern
• singleton (9 facts) - A pattern that ensures that a certain class can have only one instance