pass interface to itself is bad practice?

Question

Would it be considered bad to pass an interface to itself through a method on that interface? To me this seems like it would be bad practice but if someone can help that would be great?

an example

ISomeInterface someInterface1 = new SomeObject1();
ISomeInterface someInterface2 = new SomeObject2();

var someReturnedValue = someInterface.DoSomeWork(someInterface2);

Do you mean passing **itself** or an object of its same type? — educampver, Jun 15 '13 at 23:48
I think your question is too general. Could you include a specific example where you want to do this? — svick, Jun 16 '13 at 00:22

Pragmateek · Answer 1 · 2013-06-16T00:10:47.037

4

Here is an example where it is totally what we want:

public interface ITree
{
    void AddSubTree(ITree subTree);
}

So yes you may need to do it.

EDIT:

To be complete, you may want to use an object with itself too:

public class NetworkInterface
{
    public void ConnectTo(NetworkInterface otherInterface)
    {
    }
}

...

NetworkInterface localhost = new NetworkInterface();
localhost.ConnectTo(localhost);

edited Jun 16 '13 at 00:10

answered Jun 15 '13 at 23:50

Pragmateek

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The reasoning behind this logic used is to avoid the original logic used which was to pass two objects into a method and have the called method determine which combination of the two objects was passed in. Leading to a long if-else statement in the called method. – chuckd Jun 16 '13 at 02:21
Have you a concrete example? Because seems like you could do this with **inheritance**, overriding a given method in sub-classes or with the **visitor pattern** if what you want is **double-dispatch**. – Pragmateek Jun 16 '13 at 13:15

score 0 · Answer 2 · answered Jun 16 '13 at 00:06

It depends on what you do with that. If you know what are you doing it's good, if you don't know what are you doing try and create a prototype see if your design work.

As a general guideline using the same interface within itself is NOT a bad practice.

Good example of interface that use object of the same interface inside themself are given by the composite pattern and the decorator pattern.

pass interface to itself is bad practice?

2 Answers2