Bringing your application into 2014

This should probably be titled "A practical guide to surviving legacy code"

Slides with speaker notes can be found at http://cl.ly/470i2k2O2T1U

Transcript

1. Bringing your application into 2014
2. Refactoring your application in 2014
3. Refactoring your application
4. A practical guide to surviving legacy code
5. A practical guide to surviving any code
6. I’m Michael! • @mheap on Twitter • Fifth time at PHPNW! • Developer at…
8. Let me paint you a picture
9. Job interview
10. Job offer
11. 10am Start
12. Awesome workstation
13. $dbhost = 'localhost:3036';! $dbuser = 'root';! $dbpass = 'rootpassword';! $conn = mysql_connect($dbhost, $dbuser, $dbpass);! if(! $conn )! {! die('Could not connect: ' . mysql_error());! }! $sql = 'SELECT id, name FROM employee';! ! mysql_select_db('test_db');! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! echo "EMP ID :{$row['id']} <br> ".! "EMP NAME : {$row['name']} <br> ".! "--------------------------------<br>";! } ! echo "Fetched data successfully\n";! mysql_close($conn);!
14. The harsh truth
15. All code is legacy code
16. Not about intentions
17. Fixing it
18. Disclaimer
19. Why put the effort in?
20. Reduce complexity
21. Increase maintainability
22. Improve performance
23. Better stability
24. Prerequisites
25. Refactor != Rewrite
26. No new functionality
27. Modern PHP
28. Version control
29. Choose a standard
30. Leave the code a little better than you found it
31. PSR
32. PSR0/4
33. PSR2
34. Request lifecycle
35. Dependency
36. Action
37. Response
38. What about our code?
39. <?php! ! $dbhost = 'localhost:3036';! $dbuser = 'root';! $dbpass = 'rootpassword';! $conn = mysql_connect($dbhost, $dbuser, $dbpass);! if(! $conn )! {! die('Could not connect: ' . mysql_error());! }! $sql = 'SELECT id name FROM employee';! ! mysql_select_db('test_db');! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! echo "EMP ID :{$row['id']} <br> ".! "EMP NAME : {$row['name']} <br> ".! "--------------------------------<br>";! } ! echo "Fetched data successfully\n";! mysql_close($conn);! ?>!
40. Write a test
41. Run the test
42. <?php! ! $dbhost = 'localhost:3036';! $dbuser = 'root';! $dbpass = 'rootpassword';! $conn = mysql_connect($dbhost, $dbuser, $dbpass);! if(! $conn )! {! die('Could not connect: ' . mysql_error());! }! $sql = 'SELECT id, name FROM employee';! ! mysql_select_db('test_db');! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! echo "EMP ID :{$row['id']} <br> ".! "EMP NAME : {$row['name']} <br> ".! "--------------------------------<br>";! } ! echo "Fetched data successfully\n";! mysql_close($conn);! ?>!
43. <?php! ! $dbhost = 'localhost:3036';! $dbuser = 'root';! $dbpass = 'rootpassword';! $conn = mysql_connect($dbhost, $dbuser, $dbpass);! if(! $conn )! {! die('Could not connect: ' . mysql_error());! }! $sql = 'SELECT id, name FROM employee';! ! mysql_select_db('test_db');! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! echo "EMP ID :{$row['id']} <br> ".! "EMP NAME : {$row['name']} <br> ".! "--------------------------------<br>";! } ! echo "Fetched data successfully\n";! mysql_close($conn);! ?>!
44. …! ! mysql_select_db('test_db');! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! echo "EMP ID :{$row['id']} <br> ".! "EMP NAME : {$row['name']} <br> ".! "--------------------------------<br>";! } ! ! …!
45. …! ! mysql_select_db('test_db');! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! ! $data = array();! ! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! ! $data[] = $row;! }! ! foreach ($data as $row)! echo "EMP ID :{$row['id']} <br> ".! "EMP NAME : {$row['name']} <br> ".! "--------------------------------<br>";! } ! ! …
46. …! ! $data = array(! ! array("id" => 1, "name" => "Michael ")! );! ! foreach ($data as $row)! echo "EMP ID :{$row['id']} <br> ".! "EMP NAME : {$row['name']} <br> ".! "--------------------------------<br>";! } ! ! …!
47. <?php! ! $dbhost = 'localhost:3036';! $dbuser = 'root';! $dbpass = 'rootpassword';! $conn = mysql_connect($dbhost, $dbuser, $dbpass);! if(! $conn )! {! die('Could not connect: ' . mysql_error());! }! $sql = 'SELECT id, name FROM employee';! ! mysql_select_db('test_db');! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! ! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! ! $data[] = $row;! }! ! include 'employee_view.php';! ! mysql_close($conn);! ?>!
48. <?php! ! $data = array(! ! array("id" => 1, "name" => "Michael ")! );! ! include 'employee_view.php';! ! ?>!
49. <?php! ! $dbhost = 'localhost:3036';! $dbuser = 'root';! $dbpass = 'rootpassword';! $conn = mysql_connect($dbhost, $dbuser, $dbpass);! if(! $conn )! {! die('Could not connect: ' . mysql_error());! }! $sql = 'SELECT id, name FROM employee';! ! mysql_select_db('test_db');! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! ! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! ! $data[] = $row;! }! ! include 'employee_view.php';! ! mysql_close($conn);! ?>!
50. <?php! ! $dbhost = 'localhost:3036';! $dbuser = 'root';! $dbpass = 'rootpassword';! $conn = mysql_connect($dbhost, $dbuser, $dbpass);! if(! $conn )! {! die('Could not connect: ' . mysql_error());! }! $sql = 'SELECT id, name FROM employee';! ! mysql_select_db('test_db');! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! ! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! ! $data[] = $row;! }! ! include 'employee_view.php';! ! mysql_close($conn);! ?>!
51. <?php! ! include ‘db_setup.php';! ! $sql = 'SELECT id, name FROM employee';! ! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! ! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! ! $data[] = $row;! }! ! include 'employee_view.php';! ! include ‘db_teardown.php';! ?>!
52. <?php! ! include ‘db_setup.php';! ! $sql = 'SELECT id, name FROM employee_archive’;! ! $retval = mysql_query( $sql, $conn );! if(! $retval )! {! die('Could not get data: ' . mysql_error());! }! ! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! {! ! $data[] = $row;! }! ! include 'employee_view.php';! ! include ‘db_teardown.php';! ?>!
53. <?php! ! class Db {! ! public function __construct($user, $password, $database) {! ! ! // Connection logic goes here! ! }! ! ! public function query($sql) {! ! ! $retval = mysql_query( $sql, $this->conn );! ! ! if(! $retval )! ! ! {! ! ! die('Could not get data: ' . mysql_error());! ! ! }! ! ! ! while($row = mysql_fetch_array($retval, MYSQL_ASSOC))! ! ! {! ! ! ! $data[] = $row;! ! ! }! ! ! ! return $data;! ! ! }! }!
54. <?php! ! include 'db_setup.php';! ! $data = $db->query('SELECT id, name FROM employee');! include 'employee_view.php';! ! include 'db_teardown.php';! ?>!
55. <?php! ! class EmployeeRepo {! ! public function getAllEmployees() {! ! ! global $db;! ! ! return $db->query('SELECT id, name FROM employee');! ! }! }!
56. <?php! ! class EmployeeRepo {! ! public function __construct() {! ! ! global $db;! ! ! $this->db = $db;! ! }! ! ! public function getAllEmployees() {! ! ! return $this->db->query('SELECT id, name FROM employee');! ! }! }!
57. <?php! ! include 'db_setup.php';! include 'employee_repo.php';! ! $repo = new EmployeeRepo;! $data = $repo->getAllEmployees();! include 'employee_view.php';! ! include 'db_teardown.php';! ?>!
58. class Db
59. /src/Db.php
60. class Foo_Bar_Baz
61. /src/Foo/Bar/Baz.php
62. class \mheap\Foo
63. src mheap/Foo.php
64. <?php! ! include ‘vendor/autoloader.php’;! include ‘db_setup.php’;! ! $repo = new EmployeeRepo;! $data = $repo->getAllEmployees();! include 'employee_view.php';! ?>!
65. <?php! ! class EmployeeRepo {! ! public function __construct() {! ! ! global $db;! ! ! $this->db = $db;! ! }! ! ! public function getAllEmployees() {! ! ! return $this->db->query('SELECT id, name FROM employee');! ! }! }!
66. <?php! ! class EmployeeRepo {! ! public function __construct($db) {! ! ! $this->db = $db;! ! }! ! ! public function getAllEmployees() {! ! ! return $this->db->query(‘SELECT id, name FROM employee');! ! }! }!
67. <?php! ! include ‘vendor/autoload.php';! include ‘db_setup.php’;! ! $repo = new EmployeeRepo($db);! $data = $repo->getAllEmployees();! include 'employee_view.php';! ?>!
68. <?php! ! include 'vendor/autoload.php';! include 'db_setup.php';! ! $repo = new EmployeeRepo($db);! $data = $repo->getAllEmployees();! ! $response = new Response();! ob_start();! include 'employee_view.php';! $reponse->content = ob_get_contents();! ob_end_clean();! ! $response->send();! ?>!
69. <?php! ! $this->assertEquals($response->content, "EMP ID: ...etc");! ! ?>!
70. And more!
71. Do it alongside your app
74. Review
75. Dependency
76. Action
77. Response
78. Small, reusable classes
79. Don’t change behaviour
80. Useful tools
81. PHPCS
82. PHPMD
83. PHPCPD
84. “Don’t Repeat Yourself” was never about code. It’s about knowledge. It’s about cohesion. If two pieces of code represent the exact same knowledge, they will always change together. Having to change them both is risky: you might forget one of them. On the other hand, if two identical pieces of code represent different knowledge, they will change independently. De-duplicating them introduces risk, because changing the knowledge for one object, might accidentally change it for the other object. - http://verraes.net/2014/08/dry-is-about-knowledge/
85. Qafoo Refactoring Tools
86. Scrutinizer CI
87. The parts that didn’t fit
88. Testing legacy code
89. Working with external dependencies
90. Most of the PHP-FIG work
91. Logging strategies
92. Automation
93. Effective version control
94. Find me later
95. Parting thoughts
96. Perfect is the enemy of better
97. Optimise for reading code
98. $ordersWithProducts rather than $data.
99. markReadAndNotifyUser() rather than markRead(true)
100. Constants are good
101. Code doesn't lie
102. Any questions?
103. Thank you http://joind.in/11802