• About
• Chapter 3 (Creating types in C#)
  • Interfaces
    • Explicit Interface Implementation

About

• This blog entry just goes over all of the things I found interesting and wanted to take note of when reading C# 12 in a nutshell

Chapter 3 (Creating types in C#)

Interfaces

Explicit Interface Implementation

C# allows you to explicitly allow some methods to only be called when you cast to the interface you are coding to.

  interface I1 {
    void mymethod();
  }

  interface I2 {
    void mymethod();
  }

  public class SubClass : I1, I2{
    void I1.mymethod(){
      Console.WriteLine("i1 mymethod");
    }
    void I2.mymethod(){
      Console.WriteLine("i2 mymethod");
    }
  }

• for example take these two interfaces that define the mymethod
• The Subclass implements both interfaces

In the main method we have the following code

  SubClass subClass = new();

  // output: i1 mymethod
  ((I1)subClass).mymethod();

  // output: i2 mymethod
  ((I2)subClass).mymethod();
  
  // compile time error
  subClass.mymethod();

• we have to cast to the interface to get the method to work, otherwise omitting we will get a compile time error

Use Cases

• can be used to hide members that are highly specialized and distracting to a types normal use case
  • For example a type that implements ISerializable would typically want to avoid showing those methods to the user