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(Re)discovering the SPL - PFC13

1761ecd7fe763583553dde43e62c47bd?s=47 Joshua Thijssen
September 14, 2013
65

(Re)discovering the SPL - PFC13

1761ecd7fe763583553dde43e62c47bd?s=128

Joshua Thijssen

September 14, 2013
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  1. (re)discovering Web&PHP - San Jose - USA 16-18 september 2013

    the Standard PHP Library 1
  2. 2 Joshua Thijssen Freelance consultant, developer and trainer @ NoxLogic

    Founder of the Dutch Web Alliance Development in PHP, Python, Perl, C, Java. Lead developer of Saffire. Blog: http://adayinthelifeof.nl Email: jthijssen@noxlogic.nl Twitter: @jaytaph
  3. 3 Have you ever used the SPL?

  4. 4 Have you ever used the SPL, and not want

    to apply for a job as C# developer?
  5. 5 SPL Documentation http://www.php.net/spl

  6. 6

  7. ➡ Not enough documentation. ➡ Very few examples. ➡ Wrong

    / missing in some cases. 7
  8. ➡ Adaption of the SPL will only occur when developers

    can become familiar with it. ➡ There is currently no real way to familiarize yourself with the SPL. ➡ :( 8
  9. ➡ Interfaces ➡ Iterators ➡ Data structures ➡ Exceptions ➡

    Miscellaneous functionality 9
  10. 10 Don’t get scared! The SPL is awesomesauce!

  11. 11 INTERFACES

  12. 12

  13. 13 Traversable

  14. ➡ Traversable cannot be implemented. ➡ Traversable can be detected

    (instanceof). ➡ foreach() will use traversable interfaces. 14
  15. 15 Iterator

  16. $dir = opendir("."); while (($file = readdir($dir)) !== false) {

    print "file: $file\n"; } Let’s read directory content 16
  17. $dir = opendir("."); while (($file = readdir($dir)) !== false) {

    if (! preg_match('|\.mp3$|i', $file)) { continue; } print "file: $file\n"; } 17 Filter on *.mp3
  18. ➡ Filter all MP3 and all JPG files. ➡ Filter

    all MP3 files that are larger than 6MB. ➡ Do not filter at all. ➡ Search sub-directories as well. ➡ Search multiple directories. 18
  19. ➡ How to test? ➡ How to maintain? ➡ How

    to reuse? 19 $dir = opendir("."); while (($file = readdir($dir)) !== false) { if (! preg_match('|\.mp3$|i', $file)) { continue; } print "file: $file\n"; }
  20. $it = new DirectoryIterator("."); foreach ($it as $fi) { print

    "File: ".$fi->getPathname()."\n"; } 20 Directory Iterator
  21. $it = new DirectoryIterator("."); $it = new RegexIterator($it, "/\.mp3$/i"); foreach

    ($it as $fi) { print "File: ".$fi->getPathname()."\n"; } 21 Directory Iterator + filtering
  22. $it = new DirectoryIterator("."); $it = new RegexIterator($it, "/\.mp3$/i"); $it

    = new FilesizeIterator($it, 6 * 1024 * 1024); $it = new LimitIterator($it, 10, 5); foreach ($it as $fi) { print "File: ".$fi->getPathname()."\n"; } 22 Iterator chaining
  23. ✓ Reusable We can use iterators where ever we want.

    ✓ Testable Iterators can be tested separately. ✓ Maintainable No need to adapt our business logic. 23
  24. Iterator extends Traversable { /* Methods */ abstract public mixed

    current ( void ) abstract public scalar key ( void ) abstract public void next ( void ) abstract public void rewind ( void ) abstract public boolean valid ( void ) } 24
  25. reset($a); while (current($a) !== false) { $key = key($a); $current

    = current($a); print “K: $key C: $current\n”; next($a); } Rewind() valid() 25
  26. 26 Countable

  27. $a = array(1, 2, 3); $it = new myIterator($a); print

    count($it); 1 27
  28. class myCountableIterator extends myIterator implements Countable { function count() {

    return count($this->_arr); } } $a = array(1, 2, 3, 4, 5); $it = new myCountableIterator($a); print count($it); 5 28
  29. class myCountableIterator extends myIterator implements Countable { function count() {

    return count($this->_arr); } } $a = array(1, 2, 3, 4, 5); $it = new myCountableIterator($a); $it = new limitIterator($it, 0, 3); print count($it); 1 29
  30. 30 SeekableIterator

  31. ➡ It’s not an iterator, it’s an interface. ➡ seek()

    ➡ Implementing “seekableIterator” can speed up other iterators. ➡ LimitIterator makes use of “seekableIterator” 31
  32. 32 ITERATORS

  33. SPL Iterators ➡ AppendIterator ➡ ArrayIterator ➡ CachingIterator ➡ CallbackFilterIterator

    ➡ DirectoryIterator ➡ EmptyIterator ➡ FilesystemIterator ➡ FilterIterator ➡ GlobIterator ➡ InfiniteIterator ➡ IteratorIterator ➡ LimitIterator ➡ MultipleIterator ➡ NoRewindIterator ➡ ParentIterator ➡ RecursiveArrayIterator ➡ RecursiveCachingIterator ➡ RecursiveCallbackFilterIterator ➡ RecursiveDirectoryIterator ➡ RecursiveFilterIterator ➡ RecursiveIteratorIterator ➡ RecursiveRegexIterator ➡ RecursiveTreeIterator ➡ RegexIterator ➡ SimpleXMLIterator 33
  34. SPL Iterators 34 http://lxr.php.net/xref/PHP_5_5/ext/spl/internal/

  35. ➡ IteratorIterator? ➡ RecursiveIterator? ➡ RecursiveIteratorIterator? ➡ RecursiveCallbackFilterIterator? ➡ Really!?!?

    35
  36. 36 IteratorIterator

  37. 37 Turns traversable “things” into an iterator

  38. 38 $it = new myIterator(); if ($it instanceof IteratorAggregate) {

    $it = $it->getIterator(); } $it = new LimitIterator($it, 5, 10);
  39. 39 $it = new myIterator(); $it = new IteratorIterator($it); $it

    = new LimitIterator($it, 5, 10);
  40. 40 Recursive*Iterator

  41. 41 $it = new ArrayIterator( array(“foo”, “bar”, array(“qux”, “wox”), “baz”));

    foreach ($it as $v) { print $v . “\n”; } foo bar Array baz
  42. 42 $it = new RecursiveArrayIterator( array(“foo”, “bar”, array(“qux”, “wox”), “baz”));

    foreach ($it as $v) { print $v . “\n”; } foo bar Array baz
  43. 43 $it = new RecursiveArrayIterator( array(“foo”, “bar”, array(“qux”, “wox”), “baz”));

    $it = new RecursiveIteratorIterator($it); foreach ($it as $v) { print $v . “\n”; } foo bar qux wox baz
  44. 44 “Recursive” iterators add the POSSIBILITY to recursively iterate over

    data. You still need to implement it!
  45. 45 RecursiveCallbackFilterIterator

  46. ➡ Enables recursivity ➡ Is a filter iterator (does not

    necessarily return all the elements) ➡ Filters through a callback function. 46
  47. 47 $it = new RecursiveDirectoryIterator(“/”); $it = new RecursiveCallbackFilterIterator($it, function

    ($value, $key, $it) { if ($value->isDir()) { return true; } return ($value->getSize() < 1024); }); $it = new RecursiveIteratorIterator($it); foreach ($it as $item) { print $item->getSize() . “ “ . $item->getPathName().”\n”; }
  48. 48 CachingIterator

  49. 49 2 for the price of 1

  50. 50 ➡ Lookahead iterator ➡ Caches values ➡ Powerful __tostring()

    functionality
  51. 51 $alphaIterator = new ArrayIterator(range("A", "Z")); $it = new CachingIterator($alphaIterator);

    foreach ($it as $v) { if (! $it->hasNext()) { print "last letter: "; } print $v . "\n"; } // A // ... // Y // last letter: Z
  52. 52 $alphaIterator = new ArrayIterator(range("A", "Z")); $it = new CachingIterator($alphaIterator);

    foreach ($it as $v) { if (! $it->hasNext()) { print "last letter: "; } print $v . "\n"; } print "The fourth letter of the alphabet is: ".$it[3]."\n";
  53. 53 It doesn’t use the cached data!

  54. 54 DATA STRUCTURES

  55. 55 ➡ SplDoublyLinkedList ➡ SplStack ➡ SplQueue ➡ SplHeap ➡

    SplMinHeap ➡ SplMaxHeap ➡ SplPriorityQueue ➡ SplFixedArray ➡ SplObjectStorage
  56. 56 ➡ Every data structure has its strength and weaknesses.

    ➡ Big-Oh O(1), O(n), O(log n) etc... ➡ Balance between time (CPU) and space (memory) ➡ PHP arrays aren’t bad! ➡ But sometimes other data structures are better.
  57. 57 Quiz

  58. 58 http://www.flickr.com/photos/sostark/26697448/ SplStack

  59. 59 SplQueue

  60. 60 http://www.flickr.com/photos/blogchef/4764248456/sizes/z/in/photostream/ Spl(Doubly)LinkedList

  61. 61 http://www.flickr.com/photos/pediddle/54326823/ SplObjectStorage

  62. 62 SplPriorityQueue

  63. 63 http://farm4.static.flickr.com/3224/3072017987_ee454536da.jpg SplHeap

  64. 64 http://en.wikipedia.org/wiki/File:USA.NM.VeryLargeArray.02.jpg SplFixedArray

  65. 65 ➡ Use wisely: ➡ Don’t use SplStack / SplQueue

    for random reads. ➡ Don’t use FixedArrays when you need speed boosts
  66. 66 SplObjectStorage

  67. 67 $map = new SplObjectStorage(); $map[$obj1] = $info1; $map[$obj2] =

    $info2; print_r ($map[$obj2]); $set = new SplObjectStorage(); $set->attach($obj1); print_r ($set->contains($obj1)); splObjectStorage as a set splObjectStorage as a map
  68. 68 class MyStorage extends SplObjectStorage { function getHash($object) { return

    $object->type; } } $obj1 = new StdClass(); $obj1->type = “foo”; $obj2 = new StdClass(); $obj2->type = “bar”; $obj3 = new StdClass(); $obj3->type = “foo”; $store = new MyStorage(); $store->attach($obj1); // Added $store->attach($obj2); // Added $store->attach($obj3); // Not added:same type (thus hash) already present! Defining what to store:
  69. 69 EXCEPTIONS

  70. ➡ BadFunctionCallException ➡ BadMethodCallException ➡ DomainException ➡ InvalidArgumentException ➡ LengthException

    ➡ LogicException ➡ OutOfBoundsException ➡ OutOfRangeException ➡ OverflowException ➡ RangeException ➡ RuntimeException ➡ UnderflowException ➡ UnexpectedValueException 70
  71. ➡ BadFunctionCallException ➡ BadMethodCallException ➡ DomainException ➡ InvalidArgumentException ➡ LengthException

    ➡ OutOfRangeException 71 Logic Exceptions Runtime Exceptions ➡ OutOfBoundsException ➡ OverflowException ➡ RangeException ➡ UnderflowException ➡ UnexpectedValueException
  72. 72 function foo($str) { if ($str == “The Spanish Inquisition”)

    { throw new \UnexpectedValueException(“Nobody expects ”.$str); } ... }
  73. 73 function foo($str) { if ($str == “The Spanish Inquisition”)

    { throw new \InvalidArgumentException(“Nobody expects ”.$str); } ... } Logic, not runtime
  74. 74 function foo($str, $int) { if (! is_string($str)) { throw

    new \InvalidArgumentException(“Invalid type”); } if ($int < 0 || $int > 10) { throw new \OutOfRangeException(“should be between 0 and 10); } ... }
  75. 75 class InvalidDateException extends DomainException { } class ChristmasException extends

    DomainException { } class Calendar { function addAppointment(DateTime $date, $appointment) { if ($date->format("dm") == "2512") { throw new \ChristmasException( "Cannot add appointment on christmas day"); } $weekday = $date->format("N"); if ($weekday >= 6) { throw new \InvalidDateException( "Cannot add appointment in the weekend"); } .... } }
  76. 76 Never throw “Exception” Always catch “Exception”

  77. 77 Exceptions should not be part of your flow... They’re:

    exceptions
  78. 78 MISC

  79. ➡ SPL Autoloading ➡ SplFileInfo class ➡ Spl(Temp)FileObject ➡ ArrayObject

    ➡ SplObserver / SplSubject 79
  80. 80 Autoloader

  81. 81 spl_autoload_register(“spl_autoload_call”); Throws logicException

  82. 82 spl_autoload_unregister(“spl_autoload_call”); Removes ALL the autoloaders!

  83. 83 ArrayObject

  84. 84 ArrayObjects are not objects that acts like arrays ArrayObjects

    are objects that acts like arrays
  85. 85 $a = array("foo", "bar"); $b = $a; $b[] =

    "baz"; print_r ($a); print_r ($b); Array ( [0] => foo [1] => bar ) Array ( [0] => foo [1] => bar [2] => baz )
  86. 86 $a = new ArrayObject(); $a[] = "foo"; $a[] =

    "bar"; $b = $a; $b[] = "baz"; print_r (iterator_to_array($a)); print_r (iterator_to_array($b)); Array ( [0] => foo [1] => bar [2] => baz ) Array ( [0] => foo [1] => bar [2] => baz )
  87. 87 How can we make using the SPL easier? http://noscope.com/photostream/albums/various/I_Want_To_Believe_01.jpg

  88. 88 ➡ The (first and only) book about the SPL.

    ➡ Written by me (so you know it’s good :P) ➡ Tries and fix the documentation problem of the SPL.
  89. http://farm1.static.flickr.com/73/163450213_18478d3aa6_d.jpg 89

  90. 90 Find me on twitter: @jaytaph Find me for development

    and training: www.noxlogic.nl Find me on email: jthijssen@noxlogic.nl Find me for blogs: www.adayinthelifeof.nl