Things That Can Serve as Type Parameter Constraints

A constraint on a type parameter is often a base class or interface, but can actually take on a number of different forms.

A constraint can be a class type:

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// Type parameter can be some subclass of DogToy, // e.g. SqueakyToy, RopeToy public class Dog     where TFavThing: DogToy

Or an interface type:

1 2	public class Dog     where TFavThing: IBuryable

Or another type parameter:

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// TFavThing must implement IBuryable // TOtherThing must be castable to TFavThing's type public class Dog<TFavThing,TOtherThing>     where TFavThing: IBuryable     where TOtherThing: TFavThing

class indicates that the type must be a reference type.

1 2	public class Dog<TFavThing>     where TFavThing: class

struct indicates that the type must be a non-nullable value type.

1 2	public class Dog<TFavThing>     where TFavThing: struct

new() indicates that the type must have a public parameterless constructor defined.

1 2	public class Dog<TFavThing>     where TFavThing: new()

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