2 classes implement the same interface, but a method has the same implementation across both the classes causing duplicate code

Question

Consider the following scenario:

public interface ITestInterface
{
   void TestMethod1();
   void TestMethod2();
}


public class TestParent
{
    void SomeMethod()
    {
        Console.Writeln("Method of test parent");
    }
}

public class Test1: TestParent, ITestInterface
{
  void TestMethod1()
  {
     Console.WriteLine("Implementation 1 of TestMethod1");
  }

  void TestMethod2()
  {
     Console.log("Same implementation");
  }
}

public class Test2: TestParent, ITestInterface
{
  void TestMethod1()
  {
     Console.WriteLine("Implementation 2 of TestMethod1");
  }

  void TestMethod2()
  {
     Console.log("Same implementation");
  }
}

TestParent is an existing class and Test1 and Test2 are the child classes of TestParent and implement ITestInterface.

In my above example, both the class have the same implementation for TestMethod2(). I was just wondering how to avoid duplicate code? I am planning to add couple more classes and they all have the same implementation for TestMethod2.

Add yet another class between the base class and child classes. — Wiktor Zychla
– Wiktor Zychla, Commented May 16, 2021 at 10:40

Ravi Kiran · Accepted Answer · 2021-05-16 10:52:05Z

3

You need to add an intermediate class(TestParentExtension) which extends TestParent and implements TestMethod2(). You can then extend this intermediate class for Test1 and Test2 instead of TestParent.

Here you go. I cleaned up some syntax for you.

public interface ITestInterface {
  void TestMethod1();
  void TestMethod2();
}

public class TestParent {
  public void SomeMethod() {
    Console.WriteLine("Method of test parent");
  }
}

public class IntermediateParent: TestParent {
  public void TestMethod2() {
    Console.WriteLine("Same implementation");
  }
}

public class Test1: IntermediateParent, ITestInterface {
  public void TestMethod1() {
    Console.WriteLine("Implementation 1 of TestMethod1");
  }

}

public class Test2: IntermediateParent, ITestInterface {
  public void TestMethod1() {
    Console.WriteLine("Implementation 2 of TestMethod1");
  }
}

answered May 16, 2021 at 10:52

Ravi Kiran

5851 gold badge8 silver badges22 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

kaikadi-bella Over a year ago

Thanks, I would have accepted this as an answer. But, when Tim answered I missed some context but he is kinda implying the same.

Tim Schmelter · Accepted Answer · 2021-05-16 10:43:43Z

2

Why don't you use an (abstract) base class?

public abstract class TestBase: TestParent, ITestInterface
{
    void SomeMethod()
    {
        Console.Writeln("Method of test parent");
    }

    #region ITestInterface

    public void TestMethod1()
    {
        Console.WriteLine("Implementation 1 of TestMethod1");
    }

    public void TestMethod2()
    {
        Console.log("Same implementation");
    }

    #endregion
}

public class Test1 : TestBase
{
}

public class Test2 : TestBase
{
}

edited May 16, 2021 at 10:43

answered May 16, 2021 at 10:15

Tim Schmelter

462k79 gold badges720 silver badges981 bronze badges

3 Comments

kaikadi-bella Over a year ago

I have updated my question adding some more context. TestParent is an existing class and I need to extend that class which implements the ITestInterface.

Tim Schmelter Over a year ago

@kaikadi-bella: since you have provided pseudo classes it's hard to suggest how you could refactor your code. For instance, it's not possible to let TestParent implement the interface? Or another way, let TestBase inherit from TestParent(edited my answer).

kaikadi-bella Over a year ago

TestParent cannot implement the interface because there are other derived classes of TestParent which implement some other interface. Adding TestBase inherit from TestParent will do. Thanks!

Collectives™ on Stack Overflow

2 classes implement the same interface, but a method has the same implementation across both the classes causing duplicate code

2 Answers 2

1 Comment

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related