(Re)discovering the SPL - PFC13

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(re)discovering Web&PHP - San Jose - USA 16-18 september 2013 the Standard PHP Library 1

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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: [email protected] Twitter: @jaytaph

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3 Have you ever used the SPL?

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4 Have you ever used the SPL, and not want to apply for a job as C# developer?

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5 SPL Documentation http://www.php.net/spl

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➡ Not enough documentation. ➡ Very few examples. ➡ Wrong / missing in some cases. 7

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➡ 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

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➡ Interfaces ➡ Iterators ➡ Data structures ➡ Exceptions ➡ Miscellaneous functionality 9

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10 Don’t get scared! The SPL is awesomesauce!

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11 INTERFACES

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13 Traversable

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➡ Traversable cannot be implemented. ➡ Traversable can be detected (instanceof). ➡ foreach() will use traversable interfaces. 14

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15 Iterator

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

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$dir = opendir("."); while (($file = readdir($dir)) !== false) { if (! preg_match('|\.mp3$|i', $file)) { continue; } print "file: $file\n"; } 17 Filter on *.mp3

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➡ 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

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➡ 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"; }

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$it = new DirectoryIterator("."); foreach ($it as $fi) { print "File: ".$fi->getPathname()."\n"; } 20 Directory Iterator

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

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$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

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✓ Reusable We can use iterators where ever we want. ✓ Testable Iterators can be tested separately. ✓ Maintainable No need to adapt our business logic. 23

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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

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reset($a); while (current($a) !== false) { $key = key($a); $current = current($a); print “K: $key C: $current\n”; next($a); } Rewind() valid() 25

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26 Countable

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

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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

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30 SeekableIterator

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➡ It’s not an iterator, it’s an interface. ➡ seek() ➡ Implementing “seekableIterator” can speed up other iterators. ➡ LimitIterator makes use of “seekableIterator” 31

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32 ITERATORS

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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

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SPL Iterators 34 http://lxr.php.net/xref/PHP_5_5/ext/spl/internal/

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

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36 IteratorIterator

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37 Turns traversable “things” into an iterator

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38 $it = new myIterator(); if ($it instanceof IteratorAggregate) { $it = $it->getIterator(); } $it = new LimitIterator($it, 5, 10);

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39 $it = new myIterator(); $it = new IteratorIterator($it); $it = new LimitIterator($it, 5, 10);

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40 Recursive*Iterator

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41 $it = new ArrayIterator( array(“foo”, “bar”, array(“qux”, “wox”), “baz”)); foreach ($it as $v) { print $v . “\n”; } foo bar Array baz

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

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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

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44 “Recursive” iterators add the POSSIBILITY to recursively iterate over data. You still need to implement it!

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45 RecursiveCallbackFilterIterator

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➡ Enables recursivity ➡ Is a ﬁlter iterator (does not necessarily return all the elements) ➡ Filters through a callback function. 46

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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”; }

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48 CachingIterator

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49 2 for the price of 1

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

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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

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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";

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53 It doesn’t use the cached data!

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54 DATA STRUCTURES

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55 ➡ SplDoublyLinkedList ➡ SplStack ➡ SplQueue ➡ SplHeap ➡ SplMinHeap ➡ SplMaxHeap ➡ SplPriorityQueue ➡ SplFixedArray ➡ SplObjectStorage

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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.

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57 Quiz

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

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59 SplQueue

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

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

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62 SplPriorityQueue

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

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

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65 ➡ Use wisely: ➡ Don’t use SplStack / SplQueue for random reads. ➡ Don’t use FixedArrays when you need speed boosts

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66 SplObjectStorage

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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

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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:

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69 EXCEPTIONS

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

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➡ BadFunctionCallException ➡ BadMethodCallException ➡ DomainException ➡ InvalidArgumentException ➡ LengthException ➡ OutOfRangeException 71 Logic Exceptions Runtime Exceptions ➡ OutOfBoundsException ➡ OverﬂowException ➡ RangeException ➡ UnderﬂowException ➡ UnexpectedValueException

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

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73 function foo($str) { if ($str == “The Spanish Inquisition”) { throw new \InvalidArgumentException(“Nobody expects ”.$str); } ... } Logic, not runtime

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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); } ... }

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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"); } .... } }

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76 Never throw “Exception” Always catch “Exception”

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

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78 MISC

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➡ SPL Autoloading ➡ SplFileInfo class ➡ Spl(Temp)FileObject ➡ ArrayObject ➡ SplObserver / SplSubject 79

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80 Autoloader

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81 spl_autoload_register(“spl_autoload_call”); Throws logicException

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

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83 ArrayObject

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

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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 )

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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 )

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87 How can we make using the SPL easier? http://noscope.com/photostream/albums/various/I_Want_To_Believe_01.jpg

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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.

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http://farm1.static.ﬂickr.com/73/163450213_18478d3aa6_d.jpg 89

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90 Find me on twitter: @jaytaph Find me for development and training: www.noxlogic.nl Find me on email: [email protected] Find me for blogs: www.adayinthelifeof.nl