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
   

   View Slide

2. Refactoring your application in 2014
   

   View Slide

3. Refactoring your application
   

   View Slide

4. A practical guide to surviving legacy code
   

   View Slide

5. A practical guide to surviving any code
   

   View Slide

6. I’m Michael!
   • @mheap on Twitter
   • Fifth time at PHPNW!
   • Developer at…
   

   View Slide

7. View Slide

8. Let me paint you a picture
   

   View Slide

9. Job interview
   

   View Slide

10. Job offer
    

    View Slide

11. 10am Start
    

    View Slide

12. Awesome workstation
    

    View Slide

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']}
    ".!
    "EMP NAME : {$row['name']}
    ".!
    "--------------------------------
    ";!
    } !
    echo "Fetched data successfully\n";!
    mysql_close($conn);!
    

    View Slide

14. The harsh truth
    

    View Slide

15. All code is legacy code
    

    View Slide

16. Not about intentions
    

    View Slide

17. Fixing it
    

    View Slide

18. Disclaimer
    

    View Slide

19. Why put the effort in?
    

    View Slide

20. Reduce complexity
    

    View Slide

21. Increase maintainability
    

    View Slide

22. Improve performance
    

    View Slide

23. Better stability
    

    View Slide

24. Prerequisites
    

    View Slide

25. Refactor != Rewrite
    

    View Slide

26. No new functionality
    

    View Slide

27. Modern PHP
    

    View Slide

28. Version control
    

    View Slide

29. Choose a standard
    

    View Slide

30. Leave the code a little better than you found it
    

    View Slide

31. PSR
    

    View Slide

32. PSR0/4
    

    View Slide

33. PSR2
    

    View Slide

34. Request lifecycle
    

    View Slide

35. Dependency
    

    View Slide

36. Action
    

    View Slide

37. Response
    

    View Slide

38. What about our code?
    

    View Slide

39. !
    $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']}
    ".!
    "EMP NAME : {$row['name']}
    ".!
    "--------------------------------
    ";!
    } !
    echo "Fetched data successfully\n";!
    mysql_close($conn);!
    ?>!
    

    View Slide

40. Write a test
    

    View Slide

41. Run the test
    

    View Slide

42. !
    $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']}
    ".!
    "EMP NAME : {$row['name']}
    ".!
    "--------------------------------
    ";!
    } !
    echo "Fetched data successfully\n";!
    mysql_close($conn);!
    ?>!
    

    View Slide

43. !
    $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']}
    ".!
    "EMP NAME : {$row['name']}
    ".!
    "--------------------------------
    ";!
    } !
    echo "Fetched data successfully\n";!
    mysql_close($conn);!
    ?>!
    

    View Slide

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']}
    ".!
    "EMP NAME : {$row['name']}
    ".!
    "--------------------------------
    ";!
    } !
    !
    …!
    

    View Slide

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']}
    ".!
    "EMP NAME : {$row['name']}
    ".!
    "--------------------------------
    ";!
    } !
    !
    …
    

    View Slide

46. …!
    !
    $data = array(!
    ! array("id" => 1, "name" => "Michael ")!
    );!
    !
    foreach ($data as $row)!
    echo "EMP ID :{$row['id']}
    ".!
    "EMP NAME : {$row['name']}
    ".!
    "--------------------------------
    ";!
    } !
    !
    …!
    

    View Slide

47. !
    $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);!
    ?>!
    

    View Slide

48. !
    $data = array(!
    ! array("id" => 1, "name" => "Michael ")!
    );!
    !
    include 'employee_view.php';!
    !
    ?>!
    

    View Slide

49. !
    $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);!
    ?>!
    

    View Slide

50. !
    $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);!
    ?>!
    

    View Slide

51. !
    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';!
    ?>!
    

    View Slide

52. !
    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';!
    ?>!
    

    View Slide

53. !
    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;!
    !
    ! }!
    }!
    

    View Slide

54. !
    include 'db_setup.php';!
    !
    $data = $db->query('SELECT id, name FROM employee');!
    include 'employee_view.php';!
    !
    include 'db_teardown.php';!
    ?>!
    

    View Slide

55. !
    class EmployeeRepo {!
    ! public function getAllEmployees() {!
    ! ! global $db;!
    ! ! return $db->query('SELECT id, name FROM employee');!
    ! }!
    }!
    

    View Slide

56. !
    class EmployeeRepo {!
    ! public function __construct() {!
    ! ! global $db;!
    ! ! $this->db = $db;!
    ! }!
    !
    ! public function getAllEmployees() {!
    ! ! return $this->db->query('SELECT id, name FROM employee');!
    ! }!
    }!
    

    View Slide

57. !
    include 'db_setup.php';!
    include 'employee_repo.php';!
    !
    $repo = new EmployeeRepo;!
    $data = $repo->getAllEmployees();!
    include 'employee_view.php';!
    !
    include 'db_teardown.php';!
    ?>!
    

    View Slide

58. class Db
    

    View Slide

59. /src/Db.php
    

    View Slide

60. class Foo_Bar_Baz
    

    View Slide

61. /src/Foo/Bar/Baz.php
    

    View Slide

62. class \mheap\Foo
    

    View Slide

63. src mheap/Foo.php
    

    View Slide

64. !
    include ‘vendor/autoloader.php’;!
    include ‘db_setup.php’;!
    !
    $repo = new EmployeeRepo;!
    $data = $repo->getAllEmployees();!
    include 'employee_view.php';!
    ?>!
    

    View Slide

65. !
    class EmployeeRepo {!
    ! public function __construct() {!
    ! ! global $db;!
    ! ! $this->db = $db;!
    ! }!
    !
    ! public function getAllEmployees() {!
    ! ! return $this->db->query('SELECT id, name FROM employee');!
    ! }!
    }!
    

    View Slide

66. !
    class EmployeeRepo {!
    ! public function __construct($db) {!
    ! ! $this->db = $db;!
    ! }!
    !
    ! public function getAllEmployees() {!
    ! ! return $this->db->query(‘SELECT id, name FROM employee');!
    ! }!
    }!
    

    View Slide

67. !
    include ‘vendor/autoload.php';!
    include ‘db_setup.php’;!
    !
    $repo = new EmployeeRepo($db);!
    $data = $repo->getAllEmployees();!
    include 'employee_view.php';!
    ?>!
    

    View Slide

68. !
    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();!
    ?>!
    

    View Slide

69. !
    $this->assertEquals($response->content, "EMP ID: ...etc");!
    !
    ?>!
    

    View Slide

70. And more!
    

    View Slide

71. Do it alongside your app
    

    View Slide

72. View Slide

73. View Slide

74. Review
    

    View Slide

75. Dependency
    

    View Slide

76. Action
    

    View Slide

77. Response
    

    View Slide

78. Small, reusable classes
    

    View Slide

79. Don’t change behaviour
    

    View Slide

80. Useful tools
    

    View Slide

81. PHPCS
    

    View Slide

82. PHPMD
    

    View Slide

83. PHPCPD
    

    View Slide

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/
    

    View Slide

85. Qafoo Refactoring Tools
    

    View Slide

86. Scrutinizer CI
    

    View Slide

87. The parts that didn’t fit
    

    View Slide

88. Testing legacy code
    

    View Slide

89. Working with external dependencies
    

    View Slide

90. Most of the PHP-FIG work
    

    View Slide

91. Logging strategies
    

    View Slide

92. Automation
    

    View Slide

93. Effective version control
    

    View Slide

94. Find me later
    

    View Slide

95. Parting thoughts
    

    View Slide

96. Perfect is the enemy of better
    

    View Slide

97. Optimise for reading code
    

    View Slide

98. $ordersWithProducts rather than $data.
    

    View Slide

99. markReadAndNotifyUser()
    rather than markRead(true)
    

    View Slide

100. Constants are good
     

     View Slide

101. Code doesn't lie
     

     View Slide

102. Any questions?
     

     View Slide

103. Thank you
     http://joind.in/11802
     

     View Slide