How to use Generic Constraints

Generic Constraints

Sometimes you want to limit the types that can be used in a generic. You can do that using constraints:

• where T : class – T must be a reference type.
• where T : struct – T must be a value type.
• where T : new() – T must have a parameterless constructor.
• where T : SomeBaseClass – T must inherit from SomeBaseClass.
• where T : SomeInterface – T must implement SomeInterface.
   

  public class MyClass<T> where T : class, new()
  {
      public T CreateInstance()
      {
          return new T();
      }
  }
  
  // Usage
  var myClass = new MyClass<MyType>();  // Assuming MyType is a class with a parameterless constructor

  C#

  Copy