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principles:law_of_demeter

Law of Demeter (LoD)

Variants and Alternative Names

  • Principle of Least Knowledge
  • Don't Talk to Strangers

Context

Principle Statement

“A method of an object should invoke only the methods of the following kinds of objects:

  1. itself
  2. its parameters
  3. any objects it creates/instantiates
  4. its direct component objects”1)

Description

Rationale

Strategies

Origin

Evidence

Relations to Other Principles

Generalizations

Specializations

Contrary Principles

  • More Is More Complex: Adhering to the Law of Demeter often results in additional methods.
  • Low Coupling: Adhering to the Law of Demeter may create tramp couplings which are bad.
  • High Cohesion: Adhering to the Law of Demeter often results in additional methods that mirror methods of aggregated objects. As these objects have other responsibilities, the additional methods have fewer commonalities with the “real” methods of the class, which results in a lower cohesion.

Complementary Principles

Principle Collections

Example

Description Status

Further Reading

principles/law_of_demeter.txt · Last modified: 2020-10-12 16:20 by 159.69.186.191