====== Add More Classes ======

===== Variants and Alternative Names =====


===== Context =====
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  * [[contexts:Object-Oriented Design]] 


===== Principle Statement =====

> "When things get too complex, add more classes."((Grady Booch as cited in [[wiki>AddMoreClasses]]))

===== Description =====

Complexity can often be reduced by adding further classes that better separate concerns.

===== Rationale =====


===== Strategies =====

  * Divide larger classes into several smaller ones.
  * Use polymorphism, dynamic binding and abstract couplings.


===== Caveats =====

  * Adding too many classes leads to ravioli code. Which may be hard to grasp and debug.
  * Classes need to be separately understandable (see [[Principle of Separate Understandability|PSU]]).

See section [[#contrary principles]].


===== Origin =====

Grady Booch is sometimes cited like that. The precise origin is unknown. See [[wiki>AddMoreClasses]].


===== Evidence =====
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===== Relations to Other Principles =====

==== Generalizations ====

  * [[High Cohesion]] (HC): Add more classes is a direct result of HC.

==== Specializations ====

==== Contrary Principles ====

  * [[More Is More Complex]] (MIMC): Add More Classes decreases complexity with respect to the size of the classes on expense of increased complexity due to the number of classes. There is always a tradeoff to be made. Add More Classes tells that an increased number of classes often is the lesser evil while MIMC explains the tradeoff to be made.

==== Complementary Principles ====

  * [[Encapsulate the Concept that Varies]] (ECV): ECV tells how to separate concerns when add more classes shall be used to lower complexity.
  * [[Model Principle]] (MP): While adding classes MP should be considered in order to find appropriate concepts for encapsulation into a class.


==== Principle Collections ====


===== Examples =====


===== Description Status =====
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===== Further Reading =====

  * [[wiki>AddMoreClasses]]
  * [[wiki>FearOfAddingClasses]]
  * [[wiki>HowToAvoidFearOfAddingClasses]]
  * [[wiki>MinimumNumberOfClassesAndMethods]]
  * [[wiki>RavioliCode]]
  * [[wp>Ravioli code]]

===== Discussion =====

Discuss this wiki article and the principle on the corresponding [[talk:principles:Add More Classes|talk page]].