Covariance and Contravariance

The Idea

Covariance: Presever assignment compatibility
Contravariance: Reverses assignment compatibility
Covariance and contravariance enable implicit reference conversion for array, delegate, and generic types.

In C# there are three areas where it plays an important role

  • Array Types
  • Generic Type Arguments

Covariance with Delegates

Contravariance with Delegates

Covariance with arrays

Covariance with Generics

Contravariance with Generics

Conclusion

References:

Thanks to Greg Kalapos for his video on YouTube

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