Get better at Refactoring
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You have found the more you change the code, the more difficult it becomes. Refactoring is a developer practice of improving the internal structure of an existing code without changing the external behavior. It makes code changes for present or future easier. You may have heard about Refactoring from colleagues, books, articles and have probably tried or hear it the first time. This talk presents what it is, why it is important and what you can do to get better at it based on the experience of mentoring on technical practices to others. This talk is suitable for people who want to grow their skill on creating easy to change software for themselves and others.
![@RequestMapping(value = "/send", method = RequestMethod.POST)
public String sendEmail(@Valid @ModelAttribute MailSendForm form, BindingResult result, Model model)
{
if (result.hasErrors()) {
model.addAttribute("errorMessage", "error");
return "send";
}
String[] addresses = form.getAddress().split("s*;s*");
boolean isValid = Stream.of(addresses).anyMatch(address -> !Validator.isMailAddress(address));
if (isValid) {
model.addAttribute("errorMessage", "error");
return "send";
}
for (String address : addresses) {
MailInfo mail = new MailInfo("gadget.mailsender@gmail.com", address, form.getSubject(),
form.getBody());
try {
mailService.send(mail);
} catch (Exception e) {
model.addAttribute("errorMessage", "error");
return "send";
}
}
return "send";
}
loc: 18](https://image.slidesharecdn.com/2017-171216143921/85/Get-better-at-Refactoring-6-320.jpg)
![@RequestMapping(value = "/send", method = RequestMethod.POST)
public String sendEmail(@ModelAttribute MailSendForm form, Model model) {
if (!Validator.isSubject(form.getSubject())) {
model.addAttribute("errorMessage", "error");
return "send";
}
if (!Validator.isBody(form.getBody())) {
model.addAttribute("errorMessage", "error");
return "send";
}
String addressFromForm = form.getAddress();
if (StringUtils.isEmpty(addressFromForm)) {
model.addAttribute("errorMessage", "error");
return "send";
}
String[] addresses = addressFromForm.split(";");
for(String address : addresses) {
if (!Validator.isMailAddress(address)) {
model.addAttribute("errorMessage", "error");
return "send";
}
MailInfo mail = new MailInfo("gadget.mailsender@gmail.com", address, form.getSubject(),
form.getBody());
try {
mailService.send(mail);
} catch (Exception e) {
model.addAttribute("errorMessage", "error");
}
}
return "send";
}
loc: 23](https://image.slidesharecdn.com/2017-171216143921/85/Get-better-at-Refactoring-7-320.jpg)
![@RequestMapping(value = "/send", method = RequestMethod.POST)
public String sendEmail(@Valid @ModelAttribute MailSendForm form, BindingResult result, Model model) {
if (result.hasErrors()) {
model.addAttribute("errorMessage", "error");
return "send";
}
String[] addresses = form.getAddress().split(s*;s*");
boolean isValid = Stream.of(addresses).anyMatch(address -> !Validator.isMailAddress(address));
if (isValid) {
model.addAttribute("errorMessage", "error");
return "send";
}
try {
List<MailInfo> mailInfoList = new ArrayList<>();
String subject = form.getSubject();
for (String address : addresses) {
AddressItem addressItem = addressBookService.findByAddress(address);
if (addressItem != null) {
if (StringUtils.isEmpty(addressItem.getName()) && StringUtils.contains(subject, "$name")) {
throw new Exception("name attribute is empty!!");
}
subject = StringUtils.replace(subject, "$name", addressItem.getName());
}
MailInfo mail = new MailInfo("gadget.mailsender@gmail.com", address, subject, form.getBody());
mailInfoList.add(mail);
}
mailService.sendMultiple(mailInfoList);
} catch (Exception e) {
model.addAttribute("errorMessage", "error");
return "send";
}
return "send";
loc: 26](https://image.slidesharecdn.com/2017-171216143921/85/Get-better-at-Refactoring-8-320.jpg)
![@RequestMapping(value = "/send", method = RequestMethod.POST)
public String sendEmail(@Valid @ModelAttribute MailSendForm form, BindingResult result, Model model) {
if (result.hasErrors()) {
model.addAttribute("errorMessage", "error");
return "send";
}
String[] addresses = form.getAddress().split("s*;s*");
boolean isValid = Stream.of(addresses).anyMatch(address -> !Validator.isMailAddress(address));
if (isValid) {
model.addAttribute("errorMessage", "error");
return "send";
}
try {
List<MailInfo> mailInfoList = new ArrayList<>();
String subject = form.getSubject();
for (String address : addresses) {
AddressItem addressItem = addressBookService.findByAddress(address);
String replacedSubject = subject;
if (addressItem != null) {
if (StringUtils.isEmpty(addressItem.getName()) && StringUtils.contains(subject, "$name")) {
throw new Exception("name attribute is empty!!");
}
replacedSubject = StringUtils.replace(subject, "$name", addressItem.getName());
}else {
if (StringUtils.contains(subject, "$name")){
throw new Exception("email address is not registered");
}
}
MailInfo mail = new MailInfo("gadget.mailsender@gmail.com", address, replacedSubject, form.getBody());
mailInfoList.add(mail);
}
mailService.sendMultiple(mailInfoList);
} catch (Exception e) {
model.addAttribute("errorMessage", "error");
return "send";
}
return "send";
loc: 30](https://image.slidesharecdn.com/2017-171216143921/85/Get-better-at-Refactoring-9-320.jpg)
![@RequestMapping(value = "/send", method = RequestMethod.POST)
public String sendEmail(@Valid @ModelAttribute MailSendForm form, BindingResult result, Model model) {
if (result.hasErrors()) {
model.addAttribute("errorMessage", "error");
return "send";
}
String[] addresses = form.getAddress().split("s*;s*");
boolean isValid = Stream.of(addresses).anyMatch(address -> !Validator.isMailAddress(address));
if (isValid) {
model.addAttribute("errorMessage", "error");
return "send";
}
try {
List<MailInfo> mailInfoList = new ArrayList<>();
String subject = form.getSubject();
String body = form.getBody();
for (String address : addresses) {
String replacedSubject = subject;
String replacedBody = body;
if (StringUtils.contains(subject, "$name") || StringUtils.contains(body, "$name")) {
AddressItem addressItem = addressBookService.findByAddress(address);
if (addressItem == null) {
throw new Exception("email address is not registered");
}
if (StringUtils.isEmpty(addressItem.getName())) {
throw new Exception("name attribute is empty!!");
}
replacedSubject = StringUtils.replace(subject, "$name", addressItem.getName());
replacedBody = StringUtils.replace(body, "$name", addressItem.getName());
}
MailInfo mail = new MailInfo("gadget.mailsender@gmail.com", address, replacedSubject, replacedBody);
mailInfoList.add(mail);
}
mailService.sendMultiple(mailInfoList);
} catch (Exception e) {
model.addAttribute("errorMessage", "error");
return "send";
}
return "send";
}
loc: 32](https://image.slidesharecdn.com/2017-171216143921/85/Get-better-at-Refactoring-10-320.jpg)
Get better at Refactoring
- 1. GET BETTER AT REFACTORING stanly@odd-e.com @stanlylau
- 2. INTRODUCTION ABOUT ME Lives in Singapore Software development coach / mentor Lead Agile Singapore community
- 3. @RequestMapping(value = "/send", method = RequestMethod.POST) public String post(@ModelAttribute MailSendForm form, Model model) { model.addAttribute("form", form); return "send"; } loc: 4
- 4. @RequestMapping(value = "/send", method = RequestMethod.POST) public String post(@ModelAttribute MailSendForm form, Model model) { // TODO Validate Request String address = form.getAddress(); boolean isMailAddress = Validator.isMailAddress(address); if (!isMailAddress) { model.addAttribute("form", form); model.addAttribute("error", "error"); return "send"; } String subject = form.getSubject(); boolean isSubject = Validator.isSubject(subject); String body = form.getBody(); boolean isBody = Validator.isBody(body); // TODO Mail Send // TODO Show the page model.addAttribute("form", form); return "send"; } loc: 14
- 5. @RequestMapping(value = "/sendEmail", method = RequestMethod.POST) public String sendEmail(@ModelAttribute MailSendForm form, Model model) { if (!Validator.isMailAddress(form.getAddress())) { model.addAttribute("error", "error"); return "send"; } if (!Validator.isSubject(form.getSubject())) { model.addAttribute("error", "error"); return "send"; } if (!Validator.isBody(form.getBody())) { model.addAttribute("error", "error"); return "send"; } MailInfo mail = new MailInfo("gadget.mailsender@gmail.com", form.getAddress(), form.getSubject(), form.getBody()); try { mailService.send(mail); } catch (Exception e) { e.printStackTrace(); } return "send"; } loc: 17
- 6. @RequestMapping(value = "/send", method = RequestMethod.POST) public String sendEmail(@Valid @ModelAttribute MailSendForm form, BindingResult result, Model model) { if (result.hasErrors()) { model.addAttribute("errorMessage", "error"); return "send"; } String[] addresses = form.getAddress().split("s*;s*"); boolean isValid = Stream.of(addresses).anyMatch(address -> !Validator.isMailAddress(address)); if (isValid) { model.addAttribute("errorMessage", "error"); return "send"; } for (String address : addresses) { MailInfo mail = new MailInfo("gadget.mailsender@gmail.com", address, form.getSubject(), form.getBody()); try { mailService.send(mail); } catch (Exception e) { model.addAttribute("errorMessage", "error"); return "send"; } } return "send"; } loc: 18
- 7. @RequestMapping(value = "/send", method = RequestMethod.POST) public String sendEmail(@ModelAttribute MailSendForm form, Model model) { if (!Validator.isSubject(form.getSubject())) { model.addAttribute("errorMessage", "error"); return "send"; } if (!Validator.isBody(form.getBody())) { model.addAttribute("errorMessage", "error"); return "send"; } String addressFromForm = form.getAddress(); if (StringUtils.isEmpty(addressFromForm)) { model.addAttribute("errorMessage", "error"); return "send"; } String[] addresses = addressFromForm.split(";"); for(String address : addresses) { if (!Validator.isMailAddress(address)) { model.addAttribute("errorMessage", "error"); return "send"; } MailInfo mail = new MailInfo("gadget.mailsender@gmail.com", address, form.getSubject(), form.getBody()); try { mailService.send(mail); } catch (Exception e) { model.addAttribute("errorMessage", "error"); } } return "send"; } loc: 23
- 8. @RequestMapping(value = "/send", method = RequestMethod.POST) public String sendEmail(@Valid @ModelAttribute MailSendForm form, BindingResult result, Model model) { if (result.hasErrors()) { model.addAttribute("errorMessage", "error"); return "send"; } String[] addresses = form.getAddress().split(s*;s*"); boolean isValid = Stream.of(addresses).anyMatch(address -> !Validator.isMailAddress(address)); if (isValid) { model.addAttribute("errorMessage", "error"); return "send"; } try { List<MailInfo> mailInfoList = new ArrayList<>(); String subject = form.getSubject(); for (String address : addresses) { AddressItem addressItem = addressBookService.findByAddress(address); if (addressItem != null) { if (StringUtils.isEmpty(addressItem.getName()) && StringUtils.contains(subject, "$name")) { throw new Exception("name attribute is empty!!"); } subject = StringUtils.replace(subject, "$name", addressItem.getName()); } MailInfo mail = new MailInfo("gadget.mailsender@gmail.com", address, subject, form.getBody()); mailInfoList.add(mail); } mailService.sendMultiple(mailInfoList); } catch (Exception e) { model.addAttribute("errorMessage", "error"); return "send"; } return "send"; loc: 26
- 9. @RequestMapping(value = "/send", method = RequestMethod.POST) public String sendEmail(@Valid @ModelAttribute MailSendForm form, BindingResult result, Model model) { if (result.hasErrors()) { model.addAttribute("errorMessage", "error"); return "send"; } String[] addresses = form.getAddress().split("s*;s*"); boolean isValid = Stream.of(addresses).anyMatch(address -> !Validator.isMailAddress(address)); if (isValid) { model.addAttribute("errorMessage", "error"); return "send"; } try { List<MailInfo> mailInfoList = new ArrayList<>(); String subject = form.getSubject(); for (String address : addresses) { AddressItem addressItem = addressBookService.findByAddress(address); String replacedSubject = subject; if (addressItem != null) { if (StringUtils.isEmpty(addressItem.getName()) && StringUtils.contains(subject, "$name")) { throw new Exception("name attribute is empty!!"); } replacedSubject = StringUtils.replace(subject, "$name", addressItem.getName()); }else { if (StringUtils.contains(subject, "$name")){ throw new Exception("email address is not registered"); } } MailInfo mail = new MailInfo("gadget.mailsender@gmail.com", address, replacedSubject, form.getBody()); mailInfoList.add(mail); } mailService.sendMultiple(mailInfoList); } catch (Exception e) { model.addAttribute("errorMessage", "error"); return "send"; } return "send"; loc: 30
- 10. @RequestMapping(value = "/send", method = RequestMethod.POST) public String sendEmail(@Valid @ModelAttribute MailSendForm form, BindingResult result, Model model) { if (result.hasErrors()) { model.addAttribute("errorMessage", "error"); return "send"; } String[] addresses = form.getAddress().split("s*;s*"); boolean isValid = Stream.of(addresses).anyMatch(address -> !Validator.isMailAddress(address)); if (isValid) { model.addAttribute("errorMessage", "error"); return "send"; } try { List<MailInfo> mailInfoList = new ArrayList<>(); String subject = form.getSubject(); String body = form.getBody(); for (String address : addresses) { String replacedSubject = subject; String replacedBody = body; if (StringUtils.contains(subject, "$name") || StringUtils.contains(body, "$name")) { AddressItem addressItem = addressBookService.findByAddress(address); if (addressItem == null) { throw new Exception("email address is not registered"); } if (StringUtils.isEmpty(addressItem.getName())) { throw new Exception("name attribute is empty!!"); } replacedSubject = StringUtils.replace(subject, "$name", addressItem.getName()); replacedBody = StringUtils.replace(body, "$name", addressItem.getName()); } MailInfo mail = new MailInfo("gadget.mailsender@gmail.com", address, replacedSubject, replacedBody); mailInfoList.add(mail); } mailService.sendMultiple(mailInfoList); } catch (Exception e) { model.addAttribute("errorMessage", "error"); return "send"; } return "send"; } loc: 32
- 11. DEVELOPERS GET BETTER AT COMPLEXITY AND SOMETIMES THEY BELIEVE IT IS INEVITABLE.
- 12. EXPERIENCED PROGRAMMERS DO NOT WRITE INFINITELY COMPLEX CODE; THEY WRITE CODE THATS BLINDINGLY SIMPLE 99 Bottles of OOP GROWTH OF A DEVELOPER
- 13. THE NATURE OF SOFTWARE DEVELOPMENT LEARNING THIS NATURE AND DEALING WITH IT HELPS TO INCREASE FLEXIBILITY. AMOUNT OF BAD CODE # BUGS TIME SPENT ON FIXING BUGS PANIC QUICK HACKS MOTIVATION OF DEVELOPERS REFACTORING AMOUNT OF CODE SMELLS INDICATES OPPORTUNITY FOR
- 14. IRONICALLY, DEVELOPERS ARE TOLD TO DO MORE
- 15. WHAT CAN HELP? SOFTWARE MAINTAINABILITY
- 16. REFACTORING IS A DISCIPLINED TECHNIQUE FOR RESTRUCTURING AN EXISTING BODY OF CODE, ALTERING ITS INTERNAL STRUCTURE WITHOUT CHANGING ITS EXTERNAL BEHAVIOR. MARTIN FOWLER INTRODUCE PARAMETER OBJECT EXTRACT CLASS INTRODUCE LOCAL VARIABLE RENAME MOVE METHODEXTRACT METHOD INLINE VARIABLE
- 17. REFACTORING WHY? WHAT? HOW? GET READY FOR CHANGE DESIGN CODE SMELLS
- 18. CODE SMELLS A CODE SMELL IS A SURFACE INDICATION THAT USUALLY CORRESPONDS TO A DEEPER PROBLEM IN THE SYSTEM MARTIN FOWLER DUPLICATED CODE MAGIC NUMBER FEATURE ENVY PRIMITIVE OBSESSION LONG METHOD COMMENTS
- 21. RECEIVED (NORMAL) TO: NON-CONTACT@GMAIL.COM SUBJECT: SEASONS GREETING TO: NON-CONTACT2@GMAIL.COM SUBJECT: SEASONS GREETING
- 24. RECEIVED (TEMPLATE) TO: STANLY@ODD-E.COM SUBJECT: SEASONS GREETING STANLY TO: AKI@ODD-E.COM SUBJECT: SEASONS GREETING AKI
- 25. DESIGN DIRECTION BRING OUT TEMPLATE CONCEPT
- 26. HOW TO START
- 27. HOW TO START ESSENTIAL SKILLS Explain the code with design principles Identify code smells Refactor either manually or through IDE Familiar with unit/integration tests Familiar with functionality behaviour youre changing Understand abstractions
- 28. TRY CODING DOJO SESSIONS ON PRODUCTION CODE PICK CODE SMELLS TO REMOVE
- 29. LEARN TO SMELL THE CODE CODE SMELLS
- 31. DESIGN PRINCIPLES SINGLE RESPONSIBILITY HI COHESION, LOW COUPLING
- 33. TEACH TO LEARN 1. CREATE CODE SMELLS EXERCISES 2. PRACTICE REMOVING THE SMELLS 3. INVITE PEOPLE TO REMOVE THE SMELLS 4. CODE REVIEW 5. DEMO
- 34. CRAFTSMANSHIP
- 35. REFACTORING IS AN EXERCISE IN KINDNESS Kent Beck