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immutable
subject			fact

immutable	has definition A pattern in which the instances of a class cannot change state after creation
	has context An immutable object is an object which has a state that never changes after creation. An important reason for using an immutable object is that other objects can trust its content to not unexpectedly change.
	has forces html> The immutability must be enforced. There must be no loopholes that would allow 'illegal' modification of an immutable object.
	has problem How do you create a class whose instances are immutable?
	has related patterns Read-Only Interface pattern provides the same capability as immutable, except that certain privileged classes are allowed to make changes to instances.
	has solution Ensure that the constructor of the immutable class is the only place where the values of instance variables are set or modified. If a method that would otherwise modify an instance variable must be present, then it has to return a new instance of the class.
	is a subtopic of 6.10 - The Immutable Pattern
	is an instance of design pattern
design pattern	has antipatterns zero or more antipatterns - solutions that are inferior or do not work in this context with the reason for their rejection
	has name
	has references one or more references which indicate who developed or inspired a 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

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