magpiebrain

Sam Newman's site, a Consultant at ThoughtWorks

During a pairing session today, we spotted some duplicated code and a period of refactoring ensued. The code in question related to some simple DB queries – the code for getting a connection, returning results and cleaning up was duplicated, with only the query and the exact part of the result set required being duplicated. We already had some code which could be used to remove this duplication – previously someone had written a DB visitor which was being used internally in a test class.

Extracting the visitor code out into a class in its own right was trivial. What was not was replacing the repeated code. After 10 minutes of head-scratching we had to ask ourselves the question “is this still refactoring”?

Let’s look at what we had done – we’d extracted out our visitor code to make it an object. The existing code using the visitor still worked. We couldn’t get other code using our visitor happily quickly. We decided to leave it and move on – the rational being that refactoring should be something quick you do in the normal test-code-refactor process. If you can achieve a quick win that improves code outside the scope of what you are working on, then great – but when improving code outside the purview of your current task takes too long, it feels like going off at a tangent.

Here the decision to stop came because the refactoring was taking too long – however it was in my mind still refactoring – and work that should be done at a later date. Frequently however I see people overuse the term refactoring to cover what I would think of as being redesign/re-architect. Refactoring as I see it involves small, incremental changes to the code you are working on which shouldn’t take more than five or ten minutes. What I am unsure of is how to treat those tasks that sit somewhere in between. A 5 minute change is a refactoring. A change that takes a day isn’t. What about a change that takes an hour? Or two hours?

Why should we care what is and isn’t refactoring then? Well, refactoring is an acceptable task to carry out whilst fulfilling some specific task (be it bug fixing or adding new functionality) . When you go beyond the bounds of a simple refactoring you run the risk of going off at a tangent, of loosing focus of the job at hand, without necessarily adding anything the business actually wants. Perhaps that is the answer – when you feel yourself getting too far away from the current task you know you’ve stopped refactoring and started doing something bigger.

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5 Responses to “When does refactoring become something more?”

  1. ade

    Did you back out your changes or did you leave the codebase with some code using the visitor and some code doing it the old way?
    I think we need a word for the kind of variegated code that results when people use the time a refactoring will take as a reason to only partially apply a change. Maybe it’s better to accept the duplication rather than introduce variegation–code with many different ways of doing the same thing.

    Reply
  2. Sam Newman

    We left it in as it did improve the code we wrote. We actually took another look at the original problem after a break and managed to fix it, so replacing all duplications.

    There is certainly a tradeoff between being consistently wrong and inconsistently right, and doing the best thing at the time – coding in the right way for the task at hand, where applying the ‘correct’ code across the codebase would involve significant effort (beyond the scope of what could be thought of as refactoring).

    Reply
  3. franz

    every task that keeps the algorithm the same and just change the overall structure. i.e. class, method, parameter, field, variable etc… IS A REFACTORING.
    The duration of the refactoring mainly rely to the automation of it.
    Find and factorize duplicate code is a next refactoring task to be automated (Intellij already contains plugin in order to help in this task).
    That it, that’s all. Don’t try to complexify the refactoring meaning with duration please!!!

    Reply
  4. Sam Newman

    Perhaps what I should of said is not “is something that takes more than X a refactoring” but more “is a refactoring that takes more than X something we should do”?

    Reply
  5. Abdel A Saleh

    Hi,

    I have to agree with Franz. In many instances where there is no tool to aid in automating a refactoring, the task (of refactoring) does take a fair bit of time, ie more than 10 minutes. But it is still a refactoring..

    Reply

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