contravarianceとは 意味・読み方・使い方

名詞

contravariance (countable かつ uncountable, 複数形 contravariances)

1. (object-oriented programming) The reversal of the order of data types acted upon by an operator.

   Coordinate term: covariance

   • 2005, Jesse Liberty, Visual C# 2005: A Developer's Notebook, O'Reilly Media, →ISBN, page 47:

     I get why with covariance I can return a Dog (a Dog is a Mammal), but why does contravariance work the other way? Shouldn't it accept a derived type when it expects a base type? Contravariance is consistent with Postel's Law: […]

2. (category theory) A functor which reverses composition.
3. (linear algebra) Of vectors, the property of scaling inversely with a change of basis, as opposed to covariance.

関連する語

• contravariant

Further reading

• covariance and contravariance (computer science) on Wikipedia.
• covariance and contravariance of vectors on Wikipedia.