What is Variance in Generics? (Covariance and Contravariance)

Difficulty: 5/10

covariance, contravariance, type safety

Generic Variance

Variance describes how a generic type's compatibility changes when its type parameter has an inheritance relationship. Covariance allows a generic producer of a more derived type to be used where a producer of a base type is expected. Contravariance reverses the direction and is useful for consumers: a consumer capable of accepting a base type can generally be used where a consumer of a derived type is expected. In C#, interfaces and delegates can explicitly declare variance using out and in.

javascript

1
Covariance is commonly associated with producers and uses an out-style relationship.
2
Contravariance is commonly associated with consumers and uses an in-style relationship.
3

What is Variance in Generics? (Covariance and Contravariance)

Difficulty: 5/10

covariance, contravariance, type safety

Generic Variance

javascript

1
Covariance is commonly associated with producers and uses an out-style relationship.
2
Contravariance is commonly associated with consumers and uses an in-style relationship.
3

What is Variance in Generics? (Covariance and Contravariance)

Generic Variance

What is Variance in Generics? (Covariance and Contravariance)

Generic Variance

Scenario Questions

Follow-up Questions