Phrase taken from PrinciplesOfObjectOrientedDesign:

	 :	''The NakedObjects book claims that the single most important principle of OO design is BehavioralCompleteness.''

A class is behavioral complete when all its behavior has been implemented. This doesn't mean anything except that you must EmbraceAndExtend each class on an ''as needed'' basis. SmalltalkLanguage has that property. Some libraries in JavaLanguage achieve that too.

A class can't be behavioral complete if it doesn't do the same that its parent class does and if it doesn't fulfill its responsibility.

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CategoryModelingLawsAndPrinciples