Question

In our code base

public ActionResult Copy(string id, string targetId)
            {
                //lot of similar code
                Copy(sourcePageRef, destinationPageRef);
                //lot of similar code
            }

and

public ActionResult Move(string id, string targetId)
        {
            //lot of similar code
            Move(sourcePageRef, destinationPageRef);
            //lot of similar code
        }

the problem is, Copy and Move have different signatures:

PageRef Copy(PageRef, PageRef)

and

void Move(PageRef, PageRef)

How can I refactor these methods to avoid duplication?
Thank you

Answer 1

If you don’t need the result of Copy, you could still use an Action<string, string> or whatever the type is:

public ActionResult Copy(string id, string targetId)
{
    CopyOrMove((x, y) => Copy(x, y));
}

public ActionResult Move(string id, string targetId)
{
    CopyOrMove(id, targetId, (x, y) => Move(x, y));
}

private void CopyOrMove(string id, string targetId,
                        Action<string, string> fileAction)
{
    // lot of similar code
    fileAction(sourcePageRef, destinationPageRef);
    // lot of similar code
}

That’s one option. It depends on what the “lot of similar code” is really doing, and whether the second block needs the results of the first block. For example, if you could do this:

public ActionResult Copy(string id, string targetId)
{
    string sourcePageRef = PrepareSourceFile(id, targetId);
    string targetPageRef = PrepareTargetFile(targetId);
    Copy(sourcePageRef, targetPageRef);
    CleanUp(sourcePageRef, targetPageRef);
    return ...;
}

public ActionResult Move(string id, string targetId)
{
    string sourcePageRef = PrepareSourceFile(id, targetId);
    string targetPageRef = PrepareTargetFile(targetId);
    Move(sourcePageRef, targetPageRef);
    CleanUp(sourcePageRef, targetPageRef);
    return ...;
}

… then that’s probably simpler than the refactoring-with-a-delegate approach.