How Do Generic Covariance and Contravariance Enhance Type Safety in C# 4.0?

C# 4.0 genetic collaboration and inverter detailed explanation

C# 4.0 safely achieved genetic collaboration and inverter, solving the problems of the type of security in the previous version.

Coordination and inverter allows assignment between generic types with different types of parameters. For example, the list

is now assigned to list

.

to list

), and the inverter allows to replace the type with a super type (for example, the action to the action

The co -changing method is particularly useful for returning more derived types for the method of returning to the base type. For example, Ienumeraable

Only allowed the search value to declare that Ienumeration

does not affect the type of security. On the other hand, the inverter applies to the commission. ACTION means that there is a T parameter method, which can be seamlessly converted to Action

, because any method that accepts the Object parameters can also process the string.

In short, C# 4.0 safely achieves genetic collaboration and inverting, so that more flexible and safer code can be written without affecting type integrity.

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