C#: How to design a generic class so that the type parameter must inherit a certain class?

Question

I've written a class that looks like this:

public class MyClass<T>
{
    public void doSomething()
    {
       T.somethingSpecial;
    }
}

This code doesn't compile because the compiler has no idea what T is. I would like to constrain T so that it must inherit a certain class that defines somethingSpecial . Bonus points if you can tell me how to do the same thing by contraining T so that it must implement a certain interface.

Answer 1

public class MyClass<T> where T: IAmSomethingSpecial

它被称为类型参数约束 。

Answer 2

Use the following type parameter constraint in the class declaration:

public class MyClass<T> where T : MyBaseClass

You can read more about type parameter contraints for example here at MSDN .

Answer 3

你想要的是一个通用约束 ：

public class MyClass<T> where T : SomeParentClass

Answer 4

You need a Generic Constraint :

public class MyClass<T> where T : ISomeInterface
{
  public void doSomething()
  {
    instanceOfT.somethingSpecial();
  }
}

Answer 5

Read the documentation. Generic Constraint.

class MyClass<T> where T : someinterfaceorbaseclassthatTmustinherit

Answer 6

public interface ISomeInterface
{
    void DoSomething();
}

public class MyClass<T> where T : ISomeInterface
{
    public void doSomething()
    {
       T.DoSomething();
    }
}

The where keyword allows you to specify constraints on the given generic type. You could swap out the interface for a class.