Monday, May 25, 2009

Connascence: The Underlying Principle of OO Design?

This is a great talk at a Ruby conference by Jim Weirich about his attempt to frame all object-oriented design (OOD) principles as special cases of an underlying principle called “connascence”.  Connascence is a term co-opted by Meilir Page-Jones in the ‘90s for use in OOD; below is the definition from his book with Larry Constantine entitled, “Fundamentals of Object-Oriented Design in UML” (page 214):

Connascence between two software elements A and B means either

  1. that you can postulate some change to A that would require B to be changed (or at least carefully checked) in order to perserve overall correctness, or
  2. that you can postulate some change that would require both A and B to be changed together in order to preserve overall correctness.

UPDATE: Jim Weirich's talk can be found here.

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