I stumbled upon a thread recently where the question was posed, “What are some common mistakes when refactoring code?” The answers were interesting. The more I read, the more I realized that folks weren’t talking about the same thing. They were all saying “refactor”, but many were describing scenarios that sounded more like a rewrite rather than a refactor. This is not uncommon. I’ve encountered this on multiple forums, in slack discussions, in blog posts, and in actual human to human conversation (it happens). Words matter in communication. Really, they do. You don’t have to be a Lexicographer. But you might want to make sure you know the meaning of the words you do use. And know their meaning in the specific context within which you are using them. Do a little research. Assume you don’t know and seek to understand. Words convey concepts. When we misuse a word or lack a shared definition, we diminish the ability to maintain a shared understanding; we diminish our ability to communicate. It’s hard enough when we all agree on the meaning of the words we’re using. You see, much of the advice given was helpful from the perspective of a rewrite. “Make sure you fully understand what the old code does.”, “Make sure you have sufficient time.”, and even “Make sure your manager approves.” - These are all reasonable things to consider when rewriting a piece of code or an entire application. These are not necessary or perhaps even appropriate when it comes to refactoring. What does Refactor mean? From Wikipedia : This article is about a behaviour-preserving change. It is not to be confused with Rewrite (programming) . is the process of restructuring existing computer code—changing the —without changing its external behavior. Refactoring is intended to improve attributes of the . Advantages include improved code and reduced ; these can improve and create a more expressive internal or to improve . Code refactoring factoring nonfunctional software readability complexity source-code maintainability architecture object model extensibility Typically, refactoring applies a series of standardised basic , each of which is (usually) a tiny change in a 's source code that either preserves the behaviour of the software, or at least does not modify its conformance to . Many provide automated support for performing the mechanical aspects of these basic refactorings. If done well, code refactoring may help software developers discover and fix hidden or dormant or in the system by simplifying the underlying logic and eliminating unnecessary levels of complexity. If done poorly it may fail the requirement that external functionality not be changed, introduce new bugs, or both. micro-refactorings computer program functional requirements development environments bugs vulnerabilities From Agile Alliance - Refactoring consists of improving the internal structure of an existing program’s source code, while preserving its external behavior. The noun “refactoring” refers to one particular behavior-preserving transformation, such as “Extract Method” or “Introduce Parameter.” Common Pitfalls Refactoring does “not” mean: rewriting code fixing bugs improve observable aspects of software such as its interface From Refactoring.com - is a disciplined technique for restructuring an existing body of code, altering its internal structure without changing its external behavior. Refactoring Its heart is a series of small behavior preserving transformations. Each transformation (called a "refactoring") does little, but a sequence of these transformations can produce a significant restructuring. Since each refactoring is small, it's less likely to go wrong. The system is kept fully working after each refactoring, reducing the chances that a system can get seriously broken during the restructuring. We All Seem to Agree Refactor is not a word in the common lexicon. As far as I know, it is specific to software development. While factoring is a thing in mathematics, the notion of refactoring doesn’t exist. Or more accurately, the word refactoring is not a part of the mathematic lexicon. As we look across these definitions, there are some common elements: Restructuring existing code Preserving behavior Taking small, safe steps Not the same as re-writing As an industry, we all seem to agree that refactoring is restructuring existing code in small safe steps while preserving the behavior of the system. We also agree that it is not re-writing code, but a definition should describe what a thing is. What does Rewrite mean? From Wikipedia - This article is about code rewrites, where it is expected that the behavior will change. It is not to be confused with Code refactoring . A in is the act or result of re-implementing a large portion of existing functionality without re-use of its or . When the rewrite is not using existing code at all, it is common to speak of a . rewrite computer programming source code writing inscription rewrite from scratch From Merriam-Webster - rewrite : to write (something) again especially in a different way in order to improve it or to include new information. reprogram to program anew to revise or write a new program for : especially : to rewrite or revise a program especially of a computer : We All Seem to Agree Rewrite is a word in the common lexicon. It means different things in differing contexts. I’ve tried to find definitions specific to software. As we look across these definitions, there are some common elements: Programming anew Changing behavior - at least not strictly validating existing behavior Large steps As an industry, we seem to agree that rewriting is a re-implementation (writing anew) of a large portion of an application. So what? This wouldn’t be the first time I was accused of being pedantic or worrying about unnecessary semantics. I’ve been railing on about for well over a decade. Technical Debt But, it does matter. Refactoring is a specific discipline that reduces risk rather than introducing it. Refactoring is beneficial. Refactoring is a skill that all developers should learn and apply regularly. To misrepresent it as something to be avoided, cavalier behavior, or risk-inducing is a detriment to the industry.
