Computer Science

Refactoring: Improving the Design of Existing Code

Refactoring: Improving the Design of Existing Code

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  • Type：Epub+TxT+PDF+Mobi
  • Create Date：2021-06-06 09:52:35
  • Update Date：2025-09-07
  • Status：finish
  • Author：Martin Fowler
  • ISBN：0134757599
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Summary

Fully Revised and Updated-Includes New Refactorings and Code Examples "Any fool can write code that a computer can understand。 Good programmers write code that humans can understand。"
--M。 Fowler （1999） For more than twenty years， experienced programmers worldwide have relied on Martin Fowler's Refactoring to improve the design of existing code and to enhance software maintainability， as well as to make existing code easier to understand。
This eagerly awaited new edition has been fully updated to reflect crucial changes in the programming landscape。 Refactoring， Second Edition， features an updated catalog of refactorings and includes JavaScript code examples， as well as new functional examples that demonstrate refactoring without classes。
Like the original， this edition explains what refactoring is; why you should refactor; how to recognize code that needs refactoring; and how to actually do it successfully， no matter what language you use。
Understand the process and general principles of refactoring Quickly apply useful refactorings to make a program easier to comprehend and change Recognize "bad smells" in code that signal opportunities to refactor Explore the refactorings， each with explanations， motivation， mechanics， and simple examples Build solid tests for your refactorings Recognize tradeoffs and obstacles to refactoring Includes free access to the canonical web edition， with even more refactoring resources。 （See inside the book for details about how to access the web edition。）

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Reviews

Michael Koltsov ，

This year was supposed to be full of reading and learning new things， but the reality has shown that it had different plans for my time。 That's why it took me much longer that usual to finish this book and therefore I may forget some of the things that I found interesting in it。I must admit that as a writer Martin Fowler has his unique style that you start to grasp after finishing just a few pages of any of his books。 He's one of the father figures of the "make code for humans not for the machin This year was supposed to be full of reading and learning new things， but the reality has shown that it had different plans for my time。 That's why it took me much longer that usual to finish this book and therefore I may forget some of the things that I found interesting in it。I must admit that as a writer Martin Fowler has his unique style that you start to grasp after finishing just a few pages of any of his books。 He's one of the father figures of the "make code for humans not for the machines" movement that some may also call "clean code & architecture"。 It's always interesting when in his books his starts to mention his buddies who'd contributed a lot to make developer's life easier。 In this book for example I found out that "smelly code" saying was invented because Kent Beck had to fight two things simultaneously: someone's bad code as well as smelly diapers。 A quick glance to other people's lives is something that you can't often find in technical books。Speaking of the book itself I don't think that there was much to be surprised about since the first edition。 More controversial refactoring methods have been added， it always frightens me when one example contradicts with the one that you read a few pages ago。 But that's the art of writing elegant code that can pass code reviews。 You never know what type of refactoring will be useful until you try all of them。 And some of them can be opposite to one another， but that what makes good developers artists not just craftsmen。I enjoyed the choice of switching to Javascript to illustrate the refactorings。 It made the book much more concise and at the same time if JS is not your primary language it makes you think how this or that example would work in your language。 That's the right way to go in my opinion。 。。。more

Shyamsundar Parthasarathy ，

Nice book with lot of practical examples that ground the theory。

Suclogger ，

大师之作，计算机科学领域足以放入名人堂的作品。轻松的文笔能传达通透的观点，作者对于重构概念的理解和把握让人叹服。唯一读过类似的文风的作品是《The Pragmatic Programmer: Your Journey to Mastery》，都是大师之作。这本书躺在我的书架上许久了，长期以来因为他的厚实让人望而生畏，没想到翻开后，2天地铁+午间，再加今天出差空暇的下午时间就读完了。一方面归功于作者的深入浅出的文笔，另一方面是因为，作者传达的观点，在我的编程生涯中已经从方方面面渗透进我的常识，并已经不自觉的实践过了，这一现象，不得不更让人叹服本书观点的开创性，远见性，已经长久的活力证明的正确性。更让人惊艳的是，书的末尾还从观点和软件推广的角度做了思考，对于技术传播的理论做了探讨，虽然只是寥寥数笔，但是对于我们见怪不怪的重复造轮子却不推广轮子的现象有所针指。本书不适合初学编程的读者，推荐每位有初-中级编程经验的读者开卷，你一定不会后悔。

Dhruv Bhatnagar ，

Good book for new developers as well as those who have good work experience。 This book provides a sort of mental model（s） for refactoring code。 The book is well divided into small chunks and you can navigate easily and finish the book fast。

Matthew King ，

It was a good read but seemed targeted towards developers early in the career （i。e。 would be extremely beneficial if you're in college or not as exposed to the field quite yet）。 Most of the mid to later chapters were refactorings I've seen performed on the job （frequently）， but they weren't exactly "labeled"。 That said， it contains a ton of useful information and I was able to save several snippets in the book for later reference as I grow as a developer myself。 It was a good read but seemed targeted towards developers early in the career （i。e。 would be extremely beneficial if you're in college or not as exposed to the field quite yet）。 Most of the mid to later chapters were refactorings I've seen performed on the job （frequently）， but they weren't exactly "labeled"。 That said， it contains a ton of useful information and I was able to save several snippets in the book for later reference as I grow as a developer myself。 。。。more

Sepehr ，

The must-read catalog。

Suphan Fayong ，

There are 12 chapters。 The content is basic up to chapter 9 and starts interesting at chapter 10。 Most of the examples are straightforward。 Still， they are great for beginners。 A few years of coding experience is required to appreciate this book。 However， if you have a lot of coding experience and improve yourself for so long， this book might be too easy。Some of the ideas in this book are controversy， but I think it is fine since this is the nature of books about cleaning code。

هدى ，

If you don't like reading books you can scan this websitehttps://refactoring。guru/refactoringIt's the same but briefer and more orgnaized If you don't like reading books you can scan this websitehttps://refactoring。guru/refactoringIt's the same but briefer and more orgnaized 。。。more

Yury Jefse ，

Gostei da estrutura do livro， de como é claro ao explicar cada técnica， e como é aplicado。 Os códigos da edição que li， que é a segunda， é escrito em Javascript já seguindo as tecnologias que estão badaladas no mercado。 Vale ressaltar que esse livro é mais indicado para iniciantes até intermediário。 Se você é avançado e espera coisas novas aqui， infelizmente você vai se frustrar; mas caso queira reforçar conceitos e técnicas de boas práticas， esse livro é bom。

Burak IŞIK ，

Refactor， Compile， Test Cycle！

John Smith ，

Even a little bit old already， I like the style and the examples。 They were quite helpful during my last project！ Kudos！

Gencho ，

Lots of nice tips and tricks。 Easy to read and follow！ Recommend it！

Adam Rice ，

Fowler really does try to provide a generic guide for refactoring and his commitment to keeping it updated should be applauded。 Unfortunately， however， there can be quite substantial differences between languages that can render a large number of the examples not valuable in my primary language， Ruby。 I tried to re-build every example in Ruby to create a collection of relevant refactoring examples but found I was contorting myself into very unusual positions。There is an old Ruby Edition of this Fowler really does try to provide a generic guide for refactoring and his commitment to keeping it updated should be applauded。 Unfortunately， however， there can be quite substantial differences between languages that can render a large number of the examples not valuable in my primary language， Ruby。 I tried to re-build every example in Ruby to create a collection of relevant refactoring examples but found I was contorting myself into very unusual positions。There is an old Ruby Edition of this book and I think I will get more out of reading that。 。。。more

Antriksh ，

Must read once for any developer， who enjoys coding ！

Daniel ，

I never had the chance to read a comprehensive resource， like this book， on "code smells" and refactoring techniques to get rid of them whether in my own code or someone else's work， until now。Code smells are basically bad practices in writing any piece of code that impedes further extension， or modification of the software and increases the complexity of the code by making it harder to understand and change。Well after reading this popular classic， which has been revised recently， it immediately I never had the chance to read a comprehensive resource， like this book， on "code smells" and refactoring techniques to get rid of them whether in my own code or someone else's work， until now。Code smells are basically bad practices in writing any piece of code that impedes further extension， or modification of the software and increases the complexity of the code by making it harder to understand and change。Well after reading this popular classic， which has been revised recently， it immediately raised to the top of my list for the best books on professional coding practices。I never felt lost during reading 400 pages of technical descriptions which is a clear sign that Martin Fowler is a fantastic communicator and a great author。I can only recommend this to the software developers of all levels， because I'm sure after reading this， you will level up in your coding skills， no matter your level。 。。。more

Djamel Benali ，

i follow the book principles， i become a better at clean code ， refactoring

David Stevenson ，

This is a review of the 2nd edition。While I thought I had a decent knowledge of what refactoring was， having read the first 100 pages of this book， I had to admit to myself that my knowledge had been shallow at best。 People in IT do have a tendency to fling terms around loosely， and “refactoring” is one of those terms。The first part of the book sorts you out in that respect， and also gives you an education about why refactoring is important and also how to go about doing it in your software deve This is a review of the 2nd edition。While I thought I had a decent knowledge of what refactoring was， having read the first 100 pages of this book， I had to admit to myself that my knowledge had been shallow at best。 People in IT do have a tendency to fling terms around loosely， and “refactoring” is one of those terms。The first part of the book sorts you out in that respect， and also gives you an education about why refactoring is important and also how to go about doing it in your software development practice。 The first 100 pages of the book is five-star material。The remainder of the book （the canonical edition of which is the web edition now， so worth checking that out for further updates since your dead tree copy was printed） is a reference to various individual refactorings that one might frequently have to reach for。 The book itself warns you that you don’t really want to read through page by page here， but after buying a book， I am typically one to read through anyway， to feel I’m maximizing the value of my purchase。 Some of the refactorings are a little tough to get through in one sitting， but some refactorings are difficult to clearly illustrate via written prose and code snippets。 To the extent it can be done I think Martin Fowler has done a great job。 But it’s hard for me to mark such as 5 stars - it’s not something I will likely ever read through page by page again， but I am no doubt better off for having done it this first time。 。。。more

Zoe ，

This book took forever to finish！ But I did it， that too in 2020。 I think the perfect time to read this is when you have started out and are a few months/years into the tech world。 Many of the refactorings are just common sense but when thinking in terms of maintainable code are quite handy。 If nothing else， definitely recommend reading the third chapter that covers the smells of bad code。

Michael ，

I went into this book with pretty large expectations。 I had heard the book was great， but I realize now I never really heard why it was great。 The rumor mill just told me that it was the book to read if you wanted to learn refactoring。Unfortunately， I found myself very disappointed by the book。 The first four chapters could be compared to Clean Code in many ways; they introduce some good practices of coding and how to perform a refactoring safely。 But beyond that it is just a reference list of a I went into this book with pretty large expectations。 I had heard the book was great， but I realize now I never really heard why it was great。 The rumor mill just told me that it was the book to read if you wanted to learn refactoring。Unfortunately， I found myself very disappointed by the book。 The first four chapters could be compared to Clean Code in many ways; they introduce some good practices of coding and how to perform a refactoring safely。 But beyond that it is just a reference list of all the different types of refactoring。 On some level I understand why he went into as much detail as he did， but there were a few that just felt extremely long-winded for how simple they are。 I don't really need an example of `rename field`。But that was another criticism I had about this book; the refactoring difficulty levels were wildly different。 Some of the refactoring steps were so simple that any modern IDE can handle it without even pausing （rename field， move declaration， delete unused code）， while others were very highly involved changes that could have long reaching impacts across the entire system， most notably "introduce polymorphism"。 So in terms of the book， renaming a variable is equivalent to introducing a series of classes and polymorphism into your application。 Perhaps what the book needs is some sort of difficulty rating， that way I at least get the sense the author realizes not all refactorings were created equal。Rants about difficult levels aside， this book really does turn into a reference book。 It simply lists every refactoring， no matter how trivial， and tells the motivation， process， and an example （or several）。 That's it。 The motivation is almost never more than a paragraph or two， so in terms of hard thinking， you won't be doing much for this book。 I would certainly not recommend this book to a programming book club; we found ourselves struggling to come up with topics of conversation at times since everything was so straightforward。 And we found ourselves skipping most， if not all， of the examples by the end of the book。 It just wasn't worth the time to read how to do the refactoring。I won't say that the book is bad， because it isn't。 And it certainly isn't a bad concept。 But I will say it wasn't an exciting book。 I didn't learn anything new that I'm excited to implement in my daily programming life。 It's like brushing my teeth; it's not fun， it's not exciting， but it's very important to do。 。。。more

Deane Barker ，

You sort of have to give this five stars， just based on reputation alone。 This is one of the great books of computer science。As the title would imply， it's about fixing the internals of computer programs， without changing how the program functions from the "outside。" This is a time-honored task in computer science -- programs get all twisted and crufty over time as they're modified and maintained， and every once in a while you have to straighten things out so you can continue working on them eas You sort of have to give this five stars， just based on reputation alone。 This is one of the great books of computer science。As the title would imply， it's about fixing the internals of computer programs， without changing how the program functions from the "outside。" This is a time-honored task in computer science -- programs get all twisted and crufty over time as they're modified and maintained， and every once in a while you have to straighten things out so you can continue working on them easily and reduce bugs。This book absolutely delivers on the promise。 It's full of "strategies" to re-organize code and make it flow better and be easier to understand。The only downside （？） is that it's not a passive book。 There are lots of code snippets （in Java） where you have to compare before and after， and follow as the author moves code around and explains why this is better。 You get a feel for what he's doing after a while， but this isn't a book where you can just kind of lay back and zone out。 To get anything out of it， you need to be _in_ this。（Also: this book is absolutely， 100% object-oriented。 All the strategies are specific to OO code， so if you're doing something else -- like functional programming -- I doubt there's much here that would help you。）In addition to the practical strategies， I enjoyed the implied philosophy behind it。 The author makes a general， overall case for writing good code， thinking clearly about what you're doing， and not being afraid to fix things that have gone bad。 。。。more

Сергей Лесничий ，

quite outdated book。 In 2020 I can't recommend this book for today's readers even with 2020 edition there are left a lot of not useful information。 I think this book can be refactored more and became thinner with list of refactoring ideas on pseudocode。Adv: - some useful ideas of refactoring - good first paragraph with refactoring exampleDis: - boilerplate code - a lot of water instead of useful ideas。 especially last paragraphs - mentioned about old language and tools that is not in use anymore quite outdated book。 In 2020 I can't recommend this book for today's readers even with 2020 edition there are left a lot of not useful information。 I think this book can be refactored more and became thinner with list of refactoring ideas on pseudocode。Adv: - some useful ideas of refactoring - good first paragraph with refactoring exampleDis: - boilerplate code - a lot of water instead of useful ideas。 especially last paragraphs - mentioned about old language and tools that is not in use anymore 。。。more

Alb85 ，

Nel libro si parla dell’importante attività di rifattorizzazione del codice。 Nel libro si elencano davvero molte tipologie di rifattorizzazioni， e per ognuna di esse si descrive:-tTipo di rifattorizzazione （in cosa consiste questa rifattorizzazione？）: In questa categoria è presente un esempio dove si vede del codice da rifattorizzare e il risultante codice dopo essere stato rifattorizzato。 Purtroppo， l’esempio utilizzato è poco descritto。-tMotivazione （quando dovremmo usare questa fattorizzazion Nel libro si parla dell’importante attività di rifattorizzazione del codice。 Nel libro si elencano davvero molte tipologie di rifattorizzazioni， e per ognuna di esse si descrive:-tTipo di rifattorizzazione （in cosa consiste questa rifattorizzazione？）: In questa categoria è presente un esempio dove si vede del codice da rifattorizzare e il risultante codice dopo essere stato rifattorizzato。 Purtroppo， l’esempio utilizzato è poco descritto。-tMotivazione （quando dovremmo usare questa fattorizzazione？）: Questa parte occupa solo un paragrafo。 Meriterebbe più spazio。-tMeccanica （Come applicare la rifattorizzazione？）: qui vengono dettagliati tutti passi per applicare la rifattorizzazione。 È la parte che occupa più spazio。 Ogni passo è accompagnato da codice。 Al giorno d’ oggi questa parte non è molto utile: molti IDE applicano le rifattorizzazioni automaticamente。 In sintesi， togliendo la parte “Meccanica”， estendendo la parte “Motivazione”， e descrivendo solo le rifattorizzazioni principali， il libro diventerebbe più snello e più denso di contenuti utili。 。。。more

Edgar Cheverier ，

Overall I think it's a good book， it has made me think twice every time I'm going to make a change or add something new。 Overall I think it's a good book， it has made me think twice every time I'm going to make a change or add something new。 。。。more

Ahmad hosseini ，

At the beginning of the book， Martin Fowler states:“My aim is to show you how to do refactoring in a controlled and efficient manner。 You will learn to refactor in such a way that you don’t introduce bugs into the code but methodically improve its structure。”Well， he has done it perfectly。There are a lot of #refactoring methods in the book that can inspire you to write better #code and improve the structure of your #software。 Some of them are complex and some of them are so simple that maybe you At the beginning of the book， Martin Fowler states:“My aim is to show you how to do refactoring in a controlled and efficient manner。 You will learn to refactor in such a way that you don’t introduce bugs into the code but methodically improve its structure。”Well， he has done it perfectly。There are a lot of #refactoring methods in the book that can inspire you to write better #code and improve the structure of your #software。 Some of them are complex and some of them are so simple that maybe you have used them before but Mr。 Fowler provided a controlled， #efficient and step by step manner for all of them。 。。。more

Robert Hernandez ，

Wow。 What a book。 I have the pleasure of finding out this book thanks to Sandi Metz’s talk at my company， and what I can share with other people interested to read this book is that there is so much more to learn from development， even if we are not necessary solving a problem， but rather how to solve comprehension。 It has tradeoffs， as noted in this book that sometimes code that is easy to understand and refactor does trade off performance solutions， but those edge cases are rare， and even then Wow。 What a book。 I have the pleasure of finding out this book thanks to Sandi Metz’s talk at my company， and what I can share with other people interested to read this book is that there is so much more to learn from development， even if we are not necessary solving a problem， but rather how to solve comprehension。 It has tradeoffs， as noted in this book that sometimes code that is easy to understand and refactor does trade off performance solutions， but those edge cases are rare， and even then there are some refactoring that can still apply。 This book uses javascript as a medium to demonstrate its refactoring but any object oriented language would suffice。 Even outside of it， functional programing gain a good amount from this book just by talking about the power of structure and code smells。 This is a book to refer to over and over again， and takes time to master but great to gain value from the first read already。 Thank you Martin Fowler。Now if there is an updated ruby one I would get in a heartbeat。 I wish there was one in each language just to see some examples in other languages :D 。。。more

Randy ，

This was a very informative and helpful book for learning about refactoring。 I read it over again from time to time。

Tony Cheang ，

If you have done some refactoring， many of these methods will be pretty familiar。 Having names for the techniques has helped my awareness， which has been good for making more atomic commits。 Good examples and a concise read—most of the book is reference—make this easy to recommend to new engineers。 The updated JS version was nice since its syntax and conventions are known territory to me （I haven’t touched much Java）， though the topic and its presentation aren’t particularly tied to the language If you have done some refactoring， many of these methods will be pretty familiar。 Having names for the techniques has helped my awareness， which has been good for making more atomic commits。 Good examples and a concise read—most of the book is reference—make this easy to recommend to new engineers。 The updated JS version was nice since its syntax and conventions are known territory to me （I haven’t touched much Java）， though the topic and its presentation aren’t particularly tied to the language。 。。。more

Fábio ，

Feels really outdated。 It's 2020 and it has being quite a while since the publication of its first edition （20 years？ 21？） and it is geared towards old java。 Also， most modern IDE can take care of most of what the book presents as in need of refactoring。 In my opinion， this book needs a new version （hopefully， a language agnostic version）。 Feels really outdated。 It's 2020 and it has being quite a while since the publication of its first edition （20 years？ 21？） and it is geared towards old java。 Also， most modern IDE can take care of most of what the book presents as in need of refactoring。 In my opinion， this book needs a new version （hopefully， a language agnostic version）。 。。。more

Akash Jain ，

Must read for any software developer

Gaurav Srivastava ，

Describes refactoring in easily comprehensible form

Reference

google book https://www.google.com/search?tbm=bks&q=Refactoring: Improving the Design of Existing Code

hathitrust digital library https://babel.hathitrust.org/cgi/ls?q1=Refactoring: Improving the Design of Existing Code&field1=ocr&a=srchls&ft=ft&lmt=ft

The British Library https://bll01.primo.exlibrisgroup.com/discovery/search?query=any,contains,Refactoring: Improving the Design of Existing Code&tab=LibraryCatalog&search_scope=Not_BL_Suppress&vid=44BL_INST:BLL01&lang=en&offset=0