C#•2w ago

✅ Default interface methods - Am I using them wrong?

I'm trying to learn when/where to properly use interfaces, and I don't understand why my default method doesn't work. I have this:

c#
public interface IMyInterface {
    string Name { get; set; }
    string JobTitle { get; set; }
    
    void Foo() { Console.WriteLine("Default Foo"); }
}

public class Person {
    public string Name { get; set; }
}

public class Employee : Person, IMyInterface {
    public string JobTitle { get; set; }
}

c#
public interface IMyInterface {
    string Name { get; set; }
    string JobTitle { get; set; }
    
    void Foo() { Console.WriteLine("Default Foo"); }
}

public class Person {
    public string Name { get; set; }
}

public class Employee : Person, IMyInterface {
    public string JobTitle { get; set; }
}

Creating a new instance of Employee should give me access to employee.Foo(), but it doesn't. Maybe I'm just overlooking something simple, but I don't understand :/

6 Replies

UnemployedNinjaOP•2w ago

I'm using .net6

Jimmacle•2w ago

you can only access DIMs by casting the object to the interface that being said, you shouldn't use DIMs for this they were added to the language mostly as a way to add new methods to interfaces in a backwards compatible way

UnemployedNinjaOP•2w ago

So DIM's are generally not very good practice to use?

Becquerel•2w ago

they are a tool meant for things like authors of libraries not so much normal application code

UnemployedNinjaOP•2w ago

!close

Accord•2w ago

Closed!

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✅ Default interface methods - Am I using them wrong?