Iterators in PHP

Transcript

1. Iterators IN PHP NOW WITH GENERATORS

2. http://bitly.com/wNwg6N

3. An iterator is an object that enables a programmer to

   traverse a container. Various types of iterators are often provided via a container's interface. Source: http://en.wikipedia.org/wiki/Iterator

4. PHP also have a lot of awesome features; at least

   two of them are in my opinion largely underused: Iterators and Streams. “ ” Fabien Potencier (Lead Developer of Symfony Project) Source: http://fabien.potencier.org/article/44/php-iterators-and-streams-are-awesome

5. One Iterator Two Iterator Three Iterator floor();

6. Where are Iterators Used?

7. Iterators in Source https://github.com/php/php-src/tree/master/ext/spl

8. Everyone Loves Iterators

9. Everyone Loves Iterators Have you used SimpleXML?

10. Everyone Loves Iterators Have you used SimpleXML? Have you used

    pdo?

11. class IterableFilterIterator extends FilterIterator { public function accept() { return

    in_array("Iterator", class_implements($this->current())); } } $classes = new IterableFilterIterator(new ArrayIterator(get_declared_classes())); foreach ($classes as $name) { echo $name . "\n"; } Classes that implement Iterator

12. class IterableFilterIterator extends FilterIterator { public function accept() { return

    in_array("Iterator", class_implements($this->current())); } } $classes = new IterableFilterIterator(new ArrayIterator(get_declared_classes())); foreach ($classes as $name) { echo $name . "\n"; } Classes that implement Iterator Generator RecursiveIteratorIterator IteratorIterator FilterIterator RecursiveFilterIterator CallbackFilterIterator RecursiveCallbackFilterIterator ParentIterator LimitIterator CachingIterator RecursiveCachingIterator NoRewindIterator AppendIterator InfiniteIterator RegexIterator RecursiveRegexIterator EmptyIterator RecursiveTreeIterator ArrayIterator RecursiveArrayIterator DirectoryIterator FilesystemIterator RecursiveDirectoryIterator GlobIterator SplFileObject SplTempFileObject SplDoublyLinkedList SplQueue SplStack SplHeap SplMinHeap SplMaxHeap SplPriorityQueue SplFixedArray SplObjectStorage MultipleIterator IntlIterator IntlPartsIterator Phar PharData SimpleXMLIterator MongoCursor

13. Defining an Iterator

14. Iterator Interfaces

15. Iterator Interfaces • Traversable • Iterator • RecursiveIterator • Countable

    • SeekableIterator Source: http://www.php.net/manual/en/spl.iterators.php

16. Interface - Iterator Source: http://us.php.net/manual/en/class.iterator.php 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 ) }

17. Interface - RecursiveIterator Source: http://www.php.net/manual/en/spl.iterators.php RecursiveIterator extends Iterator { /*

    Methods */ public RecursiveIterator getChildren ( void ) public bool hasChildren ( void ) /* Inherited methods */ abstract public mixed Iterator::current ( void ) abstract public scalar Iterator::key ( void ) abstract public void Iterator::next ( void ) abstract public void Iterator::rewind ( void ) abstract public boolean Iterator::valid ( void ) }

18. Interface - Countable Source: http://www.php.net/manual/en/spl.iterators.php Countable { /* Methods */

    abstract public int count ( void ) }

19. Interface - Seekable Source: http://www.php.net/manual/en/spl.iterators.php SeekableIterator extends Iterator { /*

    Methods */ abstract public void seek ( int $position ) /* Inherited methods */ abstract public mixed Iterator::current ( void ) abstract public scalar Iterator::key ( void ) abstract public void Iterator::next ( void ) abstract public void Iterator::rewind ( void ) abstract public boolean Iterator::valid ( void ) }

20. Iterator Basics

21. Iterator Aggregate Iterator Aggregate is used when you need to

    offload iteration, and its methods, to another iterator public function getIterator() { ... }

22. Iterator Aggregate Iterator Aggregate Iterator

23. Outer Iterator Outer Iterators act as a wrapper layer. Outer

    iterator is iterated and then internally iterates over inner iterator. * * * ITERATOR!

24. Outer Iterator Outer Iterator Inner Iterator

25. Outer Iterator Outer Iterator Inner Iterator

26. Recursive Iterator Recursive Iterators prepare an iterator to be recursively

    iterated. * Requires RecursiveIteratorIterator to properly recursively Iterate. *

27. Recursive Iterator Recursive Iterator Get Children

28. Iterator Notes If you use foreach it will auto rewind.

    Using for or while will require you to rewind iterator.

29. Recursive Iterators

30. $data = [ 'title' => 'how to work with iterators',

    'posts' => [ [ 'title' => 'introduction to iterators', 'email' => '[email protected]', ], [ 'title' => 'extending iterators', 'email' => '[email protected]', ], ], ]; foreach (new RecursiveArrayIterator($data) as $field => $val) { echo "{$field}:{$val}\n"; } Sub Title Recursive*Iterator Recursively Iterate Array

31. $data = [ 'title' => 'how to work with iterators',

    'posts' => [ [ 'title' => 'introduction to iterators', 'email' => '[email protected]', ], [ 'title' => 'extending iterators', 'email' => '[email protected]', ], ], ]; foreach (new RecursiveArrayIterator($data) as $field => $val) { echo "{$field}:{$val}\n"; } Sub Title Recursive*Iterator Recursively Iterate Array title: how to work with iterators posts: Array

32. $data = [ 'title' => 'how to work with iterators',

    'posts' => [ [ 'title' => 'introduction to iterators', 'email' => '[email protected]', ], [ 'title' => 'extending iterators', 'email' => '[email protected]', ], ], ]; foreach (new RecursiveArrayIterator($data) as $field => $val) { echo "{$field}:{$val}\n"; } Sub Title Recursive*Iterator Recursively Iterate Array title: how to work with iterators posts: Array
33. None

34. RecursiveIteratorIterator implements OuterIterator , Traversable , Iterator { /* Constants

    */ const integer LEAVES_ONLY = 0 ; const integer SELF_FIRST = 1 ; const integer CHILD_FIRST = 2 ; const integer CATCH_GET_CHILD = 16 ; }

35. $data = [ 'title' => 'how to work with iterators',

    'posts' => [ [ 'title' => 'introduction to iterators', 'email' => '[email protected]', ], [ 'title' => 'extending iterators', 'email' => '[email protected]', ], ], ]; $it = new RecursiveIteratorIterator( new RecursiveArrayIterator($data) ); foreach($it as $field => $val) { echo "{$field}:{$val}\n"; } Sub Title Recursive*Iterator Recursively Iterate Array

36. $data = [ 'title' => 'how to work with iterators',

    'posts' => [ [ 'title' => 'introduction to iterators', 'email' => '[email protected]', ], [ 'title' => 'extending iterators', 'email' => '[email protected]', ], ], ]; $it = new RecursiveIteratorIterator( new RecursiveArrayIterator($data) ); foreach($it as $field => $val) { echo "{$field}:{$val}\n"; } Sub Title Recursive*Iterator Recursively Iterate Array title: how to work with iterators title: introduction to iterators email: [email protected] title: extending iterators email: [email protected]

37. $it = new RecursiveArrayIterator([ 'Home', 'About' => ['Careers', 'Contact'], 'Location',

    'FAQ', ]); Sub Title RecursiveNavigationIterator Hooks Output multi-dimensional array as UL/LI

38. class RecursiveNavigationIterator extends RecursiveIteratorIterator { public $openTag = "<ul>"; public

    $closeTag = "</ul>"; public function beginIteration() { echo $this->openTag . PHP_EOL; } public function endIteration() { echo $this->closeTag . PHP_EOL; } public function beginChildren() { echo $this->openTag . PHP_EOL; } public function endChildren() { echo $this->closeTag . PHP_EOL; } } Sub Title RecursiveNavigationIterator Hooks Output multi-dimensional array as UL/LI

39. $it = new RecursiveArrayIterator([ 'Home', 'About' => ['Careers', 'Contact'], 'Location',

    'FAQ', ]); $navIt = new RecursiveNavigationIterator($it, RecursiveIteratorIterator::SELF_FIRST); foreach ($navIt as $navItem) { echo "<li>{$navItem}</li>" . PHP_EOL; } Sub Title RecursiveNavigationIterator Hooks Output multi-dimensional array as UL/LI

40. $it = new RecursiveArrayIterator([ 'Home', 'About' => ['Careers', 'Contact'], 'Location',

    'FAQ', ]); $navIt = new RecursiveNavigationIterator($it, RecursiveIteratorIterator::SELF_FIRST); foreach ($navIt as $navItem) { echo "<li>{$navItem}</li>" . PHP_EOL; } Sub Title RecursiveNavigationIterator Hooks Output multi-dimensional array as UL/LI <ul> <li>Home</li> <li>About</li> <ul> <li>Careers</li> <li>Contact</li> </ul> <li>Location</li> <li>FAQ</li> </ul>

41. Problem: Source: http://www.php.net/manual/en/spl.iterators.php I have a cache folder, but it

    goes many folders deep.

42. $it = new RecursiveIteratorIterator( new RecursiveDirectoryIterator('cache', FilesystemIterator::SKIP_DOTS), RecursiveIteratorIterator::CHILD_FIRST ); function

    clearCache(Iterator $it) { // Check if directory if ($it->current()->isDir()) { rmdir($it->key()); return true; } return unlink($it->key()); } iterator_apply($it, 'clearCache', [$it]); Sub Title iterator_apply Clear all files/folders in cache folder

43. Directory Iterator

44. $it = new DirectoryIterator('vendor'); foreach ($it as $file) { echo

    $file->getFilename() . PHP_EOL; } Sub Title DirectoryIterator Source: Output directory content for Composer vendors http://us.php.net/manual/en/class.directoryiterator.php SplFileInfo

45. $it = new DirectoryIterator('vendor'); foreach ($it as $file) { echo

    $file->getFilename() . PHP_EOL; } Sub Title DirectoryIterator Source: Output directory content for Composer vendors http://us.php.net/manual/en/class.directoryiterator.php SplFileInfo . .. aura autoload.php bin composer monolog psr robmorgan slim slimcontroller symfony vlucas

46. Directory Iterator Note If you attempt to access a file

    that you do not have permission to. You will receive a UnexpectedValueException.

47. Filesystem Iterator

48. FilesystemIterator extends DirectoryIterator implements SeekableIterator , Traversable , Iterator {

    /* Constants */ const integer CURRENT_AS_PATHNAME = 32 ; const integer CURRENT_AS_FILEINFO = 0 ; const integer CURRENT_AS_SELF = 16 ; const integer CURRENT_MODE_MASK = 240 ; const integer KEY_AS_PATHNAME = 0 ; const integer KEY_AS_FILENAME = 256 ; const integer FOLLOW_SYMLINKS = 512 ; const integer KEY_MODE_MASK = 3840 ; const integer NEW_CURRENT_AND_KEY = 256 ; const integer SKIP_DOTS = 4096 ; const integer UNIX_PATHS = 8192 ; // Default Flags FilesystemIterator::KEY_AS_PATHNAME FilesystemIterator::CURRENT_AS_FILEINFO FilesystemIterator::SKIP_DOTS Sub Title FileSystemIterator (PHP 5.3.x) FileSystemIterator Constants/Flags

49. Glob Iterator

50. $it = new GlobIterator('vendor/*/*.php'); foreach ($it as $path => $file)

    { echo $path . " - " . $file->getFilename() . PHP_EOL; } Sub Title GlobIterator Source: Output directory content for Composer vendors http://us.php.net/manual/en/class.globiterator.php

51. $it = new GlobIterator('vendor/*/*.php'); foreach ($it as $path => $file)

    { echo $path . " - " . $file->getFilename() . PHP_EOL; } Sub Title GlobIterator Source: Output directory content for Composer vendors http://us.php.net/manual/en/class.globiterator.php vendor/composer/ClassLoader.php - ClassLoader.php vendor/composer/autoload_classmap.php - autoload_classmap.php vendor/composer/autoload_namespaces.php - autoload_namespaces.php vendor/composer/autoload_psr4.php - autoload_psr4.php vendor/composer/autoload_real.php - autoload_real.php

52. $it = new RecursiveDirectoryIterator('vendor'); foreach (new RecursiveTreeIterator($it) as $file) {

    echo $file . PHP_EOL; } Sub Title RecursiveTreeIterator Source: Output ASCII view of Directory Structure http://us.php.net/manual/en/class.recursivetreeiterator.php

53. $it = new RecursiveDirectoryIterator('vendor'); foreach (new RecursiveTreeIterator($it) as $file) {

    echo $file . PHP_EOL; } Sub Title RecursiveTreeIterator Source: Output ASCII view of Directory Structure http://us.php.net/manual/en/class.recursivetreeiterator.php \-vendor/vlucas |-vendor/vlucas/. |-vendor/vlucas/.. \-vendor/vlucas/phpdotenv |-vendor/vlucas/phpdotenv/. |-vendor/vlucas/phpdotenv/.. |-vendor/vlucas/phpdotenv/.git | |-vendor/vlucas/phpdotenv/.git/. | |-vendor/vlucas/phpdotenv/.git/.. | |-vendor/vlucas/phpdotenv/.git/FETCH_HEAD | |-vendor/vlucas/phpdotenv/.git/HEAD | |-vendor/vlucas/phpdotenv/.git/ORIG_HEAD | |-vendor/vlucas/phpdotenv/.git/branches | | |-vendor/vlucas/phpdotenv/.git/branches/. | | \-vendor/vlucas/phpdotenv/.git/branches/.. | |-vendor/vlucas/phpdotenv/.git/config | |-vendor/vlucas/phpdotenv/.git/description

54. Filter Iterator

55. Source: http://www.php.net/manual/en/spl.iterators.php Need to view all files in a directory,

    but it keeps returning Version Control folders (.svn and .git). Problem:

56. class NoVCSIterator extends FilterIterator { public function accept() { $vcsFolders

    = array(".git", ".svn"); $file = $this->current(); if ($file->isDir() && (in_array($vcsFolders, $file->getFilename())) { return false; } return true; } } Sub Title FilterIterator Do not show Version Control folders

57. Source: http://www.php.net/manual/en/spl.iterators.php I need to see all images that are

    over 5MB that have been uploaded. Problem:

58. class LargeFileFilterIterator extends FilterIterator { public function accept() { $file

    = $this->current(); if ($file->getSize() > $this->fileSizeMin) { return true; } return false; } } class ImageFilterIterator extends FilterIterator { public function accept() { $file = $this->current(); if (in_array($file->getExtension(), $this->imageWhiteList)) { return true; } return false; } } Sub Title FilterIterator Only show images greater than 5MB

59. $dir = new FileSystemIterator(UPLOADS_PATH); $filterIt = new LargeFileFilterIterator( new ImageFilterIterator($dir,

    ['jpg']) ); foreach($filterIt as $file) { echo $file->getFileName() . PHP_EOL; } Sub Title FilterIterator Only show images greater than 5MB

60. $dir = new FileSystemIterator(UPLOADS_PATH); $filterIt = new LargeFileFilterIterator( new ImageFilterIterator($dir,

    ['jpg']) ); echo count($filterIt); // 1 echo iterator_count($filterIt); // 2 foreach($filterIt as $file) { echo $file->getFileName() . PHP_EOL; } Sub Title iterator_count Countable with Filters

61. Regex Iterator

62. /* Constants */ const integer RegexIterator->MATCH = 0 ; const

    integer GET_MATCH = 1 ; const integer ALL_MATCHES = 2 ; const integer SPLIT = 3 ; const integer REPLACE = 4 ; const integer USE_KEY = 1 ; $it = new RecursiveDirectoryIterator( 'vendor', RecursiveDirectoryIterator::SKIP_DOTS ); $regexIt = new RecursiveRegexIterator( $it, '/^.*\.(php|env|json|yml)$/', RegexIterator::ALL_MATCHES ); foreach (new RecursiveIteratorIterator($regexIt) as $path => $file) { echo $path . PHP_EOL; } Sub Title RegexIterator Source: Match specific file types with RecursiveDirectoryIterator http://us3.php.net/manual/en/class.regexiterator.php

63. /* Constants */ const integer RegexIterator->MATCH = 0 ; const

    integer GET_MATCH = 1 ; const integer ALL_MATCHES = 2 ; const integer SPLIT = 3 ; const integer REPLACE = 4 ; const integer USE_KEY = 1 ; $it = new RecursiveDirectoryIterator( 'vendor', RecursiveDirectoryIterator::SKIP_DOTS ); $regexIt = new RecursiveRegexIterator( $it, '/^.*\.(php|env|json|yml)$/', RegexIterator::ALL_MATCHES ); foreach (new RecursiveIteratorIterator($regexIt) as $path => $file) { echo $path . PHP_EOL; } Sub Title RegexIterator Source: Match specific file types with RecursiveDirectoryIterator http://us3.php.net/manual/en/class.regexiterator.php vendor/autoload.php vendor/composer/ClassLoader.php vendor/composer/autoload_classmap.php vendor/composer/autoload_namespaces.php vendor/composer/autoload_psr4.php vendor/composer/autoload_real.php vendor/composer/installed.json

64. Parent Iterator

65. Source: http://www.php.net/manual/en/spl.iterators.php Parent Iterator is a FilterIterator that only accepts

    elements that have children. Hence the name ParentIterator Parent Iterator

66. Limit Iterator

67. Source: http://www.php.net/manual/en/spl.iterators.php Currently have a CSV with a lot of

    lines, but I need to paginate with 3 results per page. Problem:

68. $usersCSV = <<<CSV "jsmith", "Jake", "Smith", "[email protected]" "saustin", "Steve", "Austin",

    "[email protected]" "srogers", "Steven", "Rogers", "[email protected]" "ballen", "Barry", "Allen", "[email protected]" "bbanner", "Bruce", "Banner", "[email protected]" CSV; $csv = new SplTempFileObject(); $csv->fwrite($usersCSV); $csv->setFlags(SplFileObject::READ_CSV); $it = new LimitIterator($csv, 0, 3); foreach ($it as list($username, $firstName, $lastName, $email)) { echo "{$firstName} {$lastName}" . PHP_EOL; } Sub Title LimitIterator Limit CSV output to first 3

69. $usersCSV = <<<CSV "jsmith", "Jake", "Smith", "[email protected]" "saustin", "Steve", "Austin",

    "[email protected]" "srogers", "Steven", "Rogers", "[email protected]" "ballen", "Barry", "Allen", "[email protected]" "bbanner", "Bruce", "Banner", "[email protected]" CSV; $csv = new SplTempFileObject(); $csv->fwrite($usersCSV); $csv->setFlags(SplFileObject::READ_CSV); $it = new LimitIterator($csv, 0, 3); foreach ($it as list($username, $firstName, $lastName, $email)) { echo "{$firstName} {$lastName}" . PHP_EOL; } Sub Title LimitIterator Limit CSV output to first 3 Jake Smith Steve Austin Steven Rogers

70. $usersCSV = <<<CSV "jsmith", "Jake", "Smith", "[email protected]" "saustin", "Steve", "Austin",

    "[email protected]" "srogers", "Steven", "Rogers", "[email protected]" "ballen", "Barry", "Allen", "[email protected]" "bbanner", "Bruce", "Banner", "[email protected]" CSV; $csv = new SplTempFileObject(); $csv->fwrite($usersCSV); $csv->setFlags(SplFileObject::READ_CSV); $it = new LimitIterator($csv, 0, 3); try { $it->seek(20); } catch (OutOfBoundsException $e) { echo "Error: " . $e->getMessage() . PHP_EOL; } Sub Title LimitIterator Throw Exception if seeking beyond total number of elements

71. $usersCSV = <<<CSV "jsmith", "Jake", "Smith", "[email protected]" "saustin", "Steve", "Austin",

    "[email protected]" "srogers", "Steven", "Rogers", "[email protected]" "ballen", "Barry", "Allen", "[email protected]" "bbanner", "Bruce", "Banner", "[email protected]" CSV; $csv = new SplTempFileObject(); $csv->fwrite($usersCSV); $csv->setFlags(SplFileObject::READ_CSV); $it = new LimitIterator($csv, 0, 3); try { $it->seek(20); } catch (OutOfBoundsException $e) { echo "Error: " . $e->getMessage() . PHP_EOL; } Sub Title LimitIterator Throw Exception if seeking beyond total number of elements Error: Cannot seek to 20 which is behind offset 0 plus count 3

72. Callback Filter Iterator

73. Source: http://www.php.net/manual/en/spl.iterators.php I need to find all files that contain

    the word “recursive”, but don’t want to create a new class to extend FilterIterator. Problem:

74. $dirIt = new GlobIterator('*.php'); $recursiveFiles = new CallbackFilterIterator( $dirIt, function($current,

    $key, $it) { return preg_match('/recursive/i', $current); } ); foreach($recursiveFiles as $name) { echo $name . PHP_EOL; } Sub Title CallbackFilterIterator CallbackFilterIterator requires PHP 5.4

75. $dirIt = new GlobIterator('*.php'); $recursiveFiles = new CallbackFilterIterator( $dirIt, function($current,

    $key, $it) { return preg_match('/recursive/i', $current); } ); foreach($recursiveFiles as $name) { echo $name . PHP_EOL; } Sub Title CallbackFilterIterator CallbackFilterIterator requires PHP 5.4 /recursive_cache.php /recursive_it.php

76. Caching Iterator

77. Source: http://www.php.net/manual/en/spl.iterators.php I need to know what value of the

    next element will be. Think prev/ next navigation. Problem:

78. $articles = new ArrayIterator([ 'NetTuts.com: Integrating Zendesk With WordPress', 'Laravel

    News: The Artisan Files Alex Dover', 'That Podcast: Episode 10 The one with the "best practices"', 'Community News: Packagist Latest Releases for 11.14.2014', ]); $it = new CachingIterator($articles); $it->rewind(); foreach ($it as $article) { echo "{$article}"; if ($it->hasNext()) { echo " --- {$it->getInnerIterator()->current()}"; } echo PHP_EOL; } Sub Title CachingIterator CachingIterator? Look Ahead Iterator! Source: http://stackoverflow.com/questions/2458099/peek-ahead-when-iterating-an-array-in-php-5-2

79. $articles = new ArrayIterator([ 'NetTuts.com: Integrating Zendesk With WordPress', 'Laravel

    News: The Artisan Files Alex Dover', 'That Podcast: Episode 10 The one with the "best practices"', 'Community News: Packagist Latest Releases for 11.14.2014', ]); $it = new CachingIterator($articles); $it->rewind(); foreach ($it as $article) { echo "{$article}"; if ($it->hasNext()) { echo " --- {$it->getInnerIterator()->current()}"; } echo PHP_EOL; } Sub Title CachingIterator CachingIterator? Look Ahead Iterator! Source: http://stackoverflow.com/questions/2458099/peek-ahead-when-iterating-an-array-in-php-5-2 NetTuts.com: Integrating Zendesk With WordPress --- Laravel News: The Artisan Files Alex Dover Laravel News: The Artisan Files Alex Dover --- That Podcast: Episode 10 The one with the "best practices" That Podcast: Episode 10 The one with the "best practices" --- Community News: Packagist Latest Releases for 11.14.2014 Community News: Packagist Latest Releases for 11.14.2014

80. Generators

81. function getLines($file) { $f = fopen($file, 'r'); if (!$f) throw

    new Exception(); while ($line = fgets($f)) { yield $line; } fclose($f); } Sub Title Generator We Have a Generator http://blog.ircmaxell.com/2012/07/what-generators-can-do-for-you.html It’s really that easy!

82. NOW IN PHP

83. function easyAsAbc() { yield 1; yield 2; yield 3; }

    foreach (easyAsAbc() as $num) { echo $num . PHP_EOL; } Sub Title Quick Tips with Yield http://us3.php.net/manual/en/language.generators.syntax.php

84. function easyAsAbc() { yield 1; yield 2; yield 3; }

    foreach (easyAsAbc() as $num) { echo $num . PHP_EOL; } Sub Title Quick Tips with Yield http://us3.php.net/manual/en/language.generators.syntax.php 1 2 3

85. function easyAsAbc() { yield 1; return; yield 2; yield 3;

    } foreach (easyAsAbc() as $num) { echo $num . PHP_EOL; } Sub Title Quick Tips with Yield http://us3.php.net/manual/en/language.generators.syntax.php End an iteration

86. function easyAsAbc() { yield 1; return; yield 2; yield 3;

    } foreach (easyAsAbc() as $num) { echo $num . PHP_EOL; } Sub Title Quick Tips with Yield http://us3.php.net/manual/en/language.generators.syntax.php End an iteration 1

87. function easyAsAbc() { yield 1; return true; yield 2; yield

    3; } foreach (easyAsAbc() as $num) { echo $num . PHP_EOL; } Sub Title Quick Tips with Yield http://us3.php.net/manual/en/language.generators.syntax.php Returning a value will cause a PHP Fatal Returning ANY VALUE will cause a PHP Fatal

88. function easyAsAbc() { yield 1; return true; yield 2; yield

    3; } foreach (easyAsAbc() as $num) { echo $num . PHP_EOL; } Sub Title Quick Tips with Yield http://us3.php.net/manual/en/language.generators.syntax.php Returning a value will cause a PHP Fatal Returning ANY VALUE will cause a PHP Fatal PHP Fatal error: Generators cannot return values using "return"

89. function userAttributes() { yield 'id' => 1; yield 'username' =>

    'jsmith'; yield 'email' => '[email protected]'; } foreach (userAttributes() as $key => $val) { echo $key . ':' . $val . PHP_EOL; } Sub Title Quick Tips with Yield http://us3.php.net/manual/en/language.generators.syntax.php Key and Value yield

90. function userAttributes() { yield 'id' => 1; yield 'username' =>

    'jsmith'; yield 'email' => '[email protected]'; } foreach (userAttributes() as $key => $val) { echo $key . ':' . $val . PHP_EOL; } Sub Title Quick Tips with Yield http://us3.php.net/manual/en/language.generators.syntax.php Key and Value yield id:1 username:jsmith email:[email protected]

91. function counter($start) { for ($i = $start; $i >= $start;

    $i++) { $command = (yield $i); if ($command == "stop") { return; } } } $counter = counter(1); foreach ($counter as $num) { if ($num >= 20) { $counter->send('stop'); } echo $num . PHP_EOL; } Receive data Quick Tips with Yield

92. function counter($start) { for ($i = $start; $i >= $start;

    $i++) { $command = (yield $i); if ($command == "stop") { return; } } } $counter = counter(1); foreach ($counter as $num) { if ($num >= 20) { $counter->send('stop'); } echo $num . PHP_EOL; } Receive data Quick Tips with Yield

93. function counter($start) { for ($i = $start; $i >= $start;

    $i++) { $command = (yield $i); if ($command == "stop") { return; } } } $counter = counter(1); foreach ($counter as $num) { if ($num >= 20) { $counter->send('stop'); } echo $num . PHP_EOL; } Receive data Quick Tips with Yield Receiving values via send method

94. function counter($start) { for ($i = $start; $i >= $start;

    $i++) { $command = (yield $i); if ($command == "stop") { return; } } } $counter = counter(1); foreach ($counter as $num) { if ($num >= 20) { $counter->send('stop'); } echo $num . PHP_EOL; } Receive data Quick Tips with Yield Receiving values via send method 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

95. Other Iterators

96. Other Iterators •EmptyIterator •If you try to access current() it

    will throw an Exception •InfiniteIterator •Continuously runs (auto rewinds)

97. Iterator Functions

98. Iterator Functions • iterator_to_array • If Iterator is Recursive, it

    will flatten array • iterator_apply • similar to array_walk • iterator_count • used when iterator doesn’t implement countable

99. Questions? Concerns? Complaints?

100. https://joind.in/12807

101. jakefolio http://jakefolio.com [email protected] Jake Smith Thanks for Listening!