This document provides advice and best practices for writing better code. It discusses topics like improving code quality through testing, refactoring, modularity and design patterns. Specific techniques mentioned include object calisthenics exercises to write simpler code, domain-driven design, and following software development principles like single responsibility and dependency inversion. The overall message is that developers should continuously work to improve their skills and write code that is easy to understand, maintain and extend over time.

1. Writing code
you won’t hate tomorrow.
Rafael Dohms
@rdohms
photo: djandyw.com

2. Staff Engineer
Rafael Dohms
jobs.usabilla.com
@rdohms on twitter

3. Staff Engineer
Rafael Dohms
jobs.usabilla.com
FeedbackFeedback
@rdohms on twitter

5. photo: Rob Allen (@akrabat)

7. REWRITE
ALL THE CODE!
image: hyperboleandahalf

8. Real Developers,
SHIP STUFF.
photo: Glyn Lowe Photoworks

12. How do we find
balance?
photo: Kalexanderson

13. Code has an
expiration date
photo: CarbonNYC

14. Code is
perishable, it rots.
photo by: massdistraction

15. Code Evolves
photo by: kevin dooley

16. Languages evolve.
photo by: raneko

17. You evolve.
photo by: Kaptain Kobold

18. Complexity
kills
Comprehension
photo: osbornb

19. Bad Design
photo: miskan

20. Bad specs

21. NIH
source: Urban dictionary
photo by: John 'K'

22. NIH
| nɒt ɪnˈventɪd hɪə |
Not Invented Here —The German art of humiliating any technology,
agricultural product, or (medical) scientific work that has not been
invented or produced in Germany, Switzerland, or Austria.
source: Urban dictionary
photo by: John 'K'

23. The Solution™
photo: Ian Sane

24. Improve code

25. Improve code
make it easier to comprehend

26. Improve code
make it easier to comprehend
make it flexible

27. Improve code
make it easier to comprehend
make it flexible
make it tested

28. Improve code
make it easier to comprehend
make it flexible
make it tested
make it easier to replace, refactor

29. Improve code
make it easier to comprehend
make it flexible
make it tested
make it easier to replace, refactor
make it not exist

30. Testing
photo by: jeffkrause

31. "Refactoring without tests
is just changing stuff."

32. Good Design
Concepts

33. Single Responsibility
Open and Close
Liskov substitution
Interface Segregation
Dependency Inversion
Singleton
Tight Coupling
Untestability
Premature Optimization
Indescriptive Naming
Duplication
Solid Stupid
○"

34. Design Patterns
photo by halloweenstock

35. Domain Driven Design
with Ubiquitous Language
photo by lwr

36. Modular Architecture
CQRS, Event Sourcing, Micro Services
photo by medialoog

37. Strict
Programming

38. Package
Managers

39. PIE
Proudly
Invented
Elsewhere

40. Readability
photo: Morgenland

41. paragraphs
photo: Trossachs Photography
whitespace

42. photo by: boston_public_library
Object Calisthenics
Jeff Bay

43. Calisthenics
/ˌkaləsˈTHeniks/
Calisthenics are a form of dynamic exercise consisting of a variety of
simple, often rhythmical, movements, generally using minimal
equipment or apparatus.
photo by: boston_public_library

44. These are
exercises, not rules. photo by: david_a_l

45. #1
Only one
indentation level
per method.
photo by: justinliew

46. #2
Do not
use else
photo by: justinliew

47. public function createPost($request)
{
$entity = new Post();
$form = new MyForm($entity);
$form->bind($request);
if ($form->isValid()){
$repository = $this->getRepository('MyBundle:Post');
if (!$repository->exists($entity) ) {
$repository->save($entity);
return $this->redirect('create_ok');
} else {
$error = "Post Title already exists";
return array('form' => $form, 'error' => $error);
}
} else {
$error = "Invalid fields";
return array('form' => $form, 'error' => $error);
}
}

48. public function createPost($request)
{
$entity = new Post();
$form = new MyForm($entity);
$form->bind($request);
if ($form->isValid()){
$repository = $this->getRepository('MyBundle:Post');
if (!$repository->exists($entity) ) {
$repository->save($entity);
return $this->redirect('create_ok');
} else {
$error = "Post Title already exists";
return array('form' => $form, 'error' => $error);
}
} else {
$error = "Invalid fields";
return array('form' => $form, 'error' => $error);
}
}
actual goal of function
“Create Post"

49. public function createPost($request)
{
$entity = new Post();
$form = new MyForm($entity);
$form->bind($request);
if ($form->isValid()){
$repository = $this->getRepository('MyBundle:Post');
if (!$repository->exists($entity) ) {
$repository->save($entity);
return $this->redirect('create_ok');
} else {
$error = "Post Title already exists";
return array('form' => $form, 'error' => $error);
}
} else {
$error = "Invalid fields";
return array('form' => $form, 'error' => $error);
}
}
this is all
error
handling

50. public function createPost($request)
{
$entity = new Post();
$form = new MyForm($entity);
$form->bind($request);
if ($form->isValid()){
$repository = $this->getRepository('MyBundle:Post');
if (!$repository->exists($entity) ) {
$repository->save($entity);
return $this->redirect('create_ok');
} else {
$error = "Post Title already exists";
return array('form' => $form, 'error' => $error);
}
} else {
$error = "Invalid fields";
return array('form' => $form, 'error' => $error);
}
}

51. public function createPost($request)
{
$entity = new Post();
$repository = $this->getRepository('MyBundle:Post');
$form = new MyForm($entity);
$form->bind($request);
if ($form->isValid() === false){
return array('form' => $form, 'error' => 'Invalid fields');
}
if ($repository->exists($entity)){
return array('form' => $form, 'error' => 'Duplicate post
title');
}
$repository->save($entity);
return $this->redirect('create_ok');
}

52. public function createPost($request)
{
$entity = new Post();
$repository = $this->getRepository('MyBundle:Post');
$form = new MyForm($entity);
$form->bind($request);
if ($form->isValid() === false){
return array('form' => $form, 'error' => 'Invalid fields');
}
if ($repository->exists($entity)){
return array('form' => $form, 'error' => 'Duplicate post
title');
}
$repository->save($entity);
return $this->redirect('create_ok');
}
exit condition 1: invalid form

53. public function createPost($request)
{
$entity = new Post();
$repository = $this->getRepository('MyBundle:Post');
$form = new MyForm($entity);
$form->bind($request);
if ($form->isValid() === false){
return array('form' => $form, 'error' => 'Invalid fields');
}
if ($repository->exists($entity)){
return array('form' => $form, 'error' => 'Duplicate post
title');
}
$repository->save($entity);
return $this->redirect('create_ok');
}
exit condition 2: duplicated post

54. public function createPost($request)
{
$entity = new Post();
$repository = $this->getRepository('MyBundle:Post');
$form = new MyForm($entity);
$form->bind($request);
if ($form->isValid() === false){
return array('form' => $form, 'error' => 'Invalid fields');
}
if ($repository->exists($entity)){
return array('form' => $form, 'error' => 'Duplicate post
title');
}
$repository->save($entity);
return $this->redirect('create_ok');
}
this is what the
method actually
does

55. public function createPost($request)
{
$repository = $this->getRepository('MyBundle:Post');
$entity = new Post();
$repository->save($entity);
return $this->redirect('create_ok');
}

56. public function createPost($request)
{
$repository = $this->getRepository('MyBundle:Post');
$entity = new Post();
$repository->save($entity);
return $this->redirect('create_ok');
}
FormValidationMiddleware
UniqueEntityMiddleware

57. public function createPost($request)
{
$repository = $this->getRepository('MyBundle:Post');
$entity = new Post();
$repository->save($entity);
return $this->redirect('create_ok');
}
The power of PSR-7
and middleware
FormValidationMiddleware
UniqueEntityMiddleware

60. #3
Wrap primitive
types, if they
contain behavior
photo by: justinliew

61. $component->repaint(false);

62. $component->repaint( new Animate(false) );

63. use MoneyMoney;
$fiveEur = Money::EUR(500);
$tenEur = $fiveEur->add($fiveEur);

64. #4
Only one
-> per line
photo by: justinliew

65. $user = $this->get('security.token_storage')->getToken()->getUser();

66. $user = $this->get('security.token_storage')->getToken()->getUser();
null

67. #5
Do not
abbreviate.
photo by: justinliew

68. if($sx >= $sy) {
if ($sx > $strSysMatImgW) {
$ny = $strSysMatImgW * $sy / $sx;
$nx = $strSysMatImgW;
}
if ($ny > $strSysMatImgH) {
$nx = $strSysMatImgH * $sx / $sy;
$ny = $strSysMatImgH;
}
}

69. #6
Keep your
classes small.
photo by: justinliew

70. #7
Limit your
instance
variables to 2
photo by: justinliew

71. class MyRegistrationService
{
protected $userService;
protected $passwordService;
protected $logger;
protected $translator;
protected $entityManager;
protected $imageCropper;
// ...
}

72. #8
Use first class
collections
photo by: justinliew

73. #9
Don’t use getters
and setters.
photo by: justinliew

74. public function getScore($request)
{
return $this->score;
}
public function setScore($score)
{
$this->score = $score;
}
$game->setScore($game->getScore() += 1);

75. public function collectedCoin()
{
$this->score += 1;
}
$game->collectedCoin();

76. #10
Document
your code.
photo by: justinliew

77. Your turn.

78. Improve
yourself!

79. Read lots of
code!

80. Write simpler
code.

81. Try Object Calisthenics
for a month.

82. Be part of this community!
Embrace open source, and
add to it!

83. DDD, Auto-wire, contribute to
PHP, write secure code, use flex,
use docker, do static analysis,
phpStan CQRS, use fixtures, be
strict, communicate, document,
collect elephpants… and all the
other amazing topics you saw
this weekend.
#phpce18

84. DDD, Auto-wire, contribute to
PHP, write secure code, use flex,
use docker, do static analysis,
phpStan CQRS, use fixtures, be
strict, communicate, document,
collect elephpants… and all the
other amazing topics you saw
this weekend.
#phpce18

85. Thank you.
http://slides.doh.ms
http://doh.ms
@rdohms
jobs.usabilla.com
looking for a job in Amsterdam?
https://joind.in/talk/18880

86. http://l.doh.ms/object-calisthenics-links
Books