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(Re)discovering the SPL - PHPWorld

Joshua Thijssen
November 13, 2014
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(Re)discovering the SPL - PHPWorld

Joshua Thijssen

November 13, 2014
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  1. 1
    Joshua Thijssen
    jaytaph
    (Re)discovering the SPL

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  2. 2
    Joshua Thijssen
    Freelance consultant and trainer @ TechAdemy
    Founder of TechAnalyze.io
    Founder of the Dutch Web Alliance
    Blog: http://adayinthelifeof.nl
    Email: [email protected]
    Twitter: @jaytaph
    Tech nalyze
    WWW.TECHANALYZE.IO

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  3. 3
    Q: Have you ever used the SPL?

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  4. 4
    Q: Have you ever used the SPL
    without going nuts?

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  5. 5
    SPL Documentation

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  6. 5
    SPL Documentation
    http://www.php.net/spl

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  7. 6

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  8. 7

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  9. 8

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  10. ➡ Not enough documentation.
    8

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  11. ➡ Not enough documentation.
    ➡ Very few examples.
    8

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  12. ➡ Not enough documentation.
    ➡ Very few examples.
    ➡ Wrong / missing in some cases.
    8

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  13. ➡ Interfaces
    ➡ Iterators
    ➡ Data structures
    ➡ Exceptions
    ➡ Miscellaneous functionality
    9
    Every SPL talk available:

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  14. 10
    Don’t get scared!
    The SPL is awesomesauce!

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  15. 11
    INTERFACES

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  16. 12
    Traversable
    (not an “spl interface”)

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  17. 13

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  18. ➡ Traversable cannot be implemented*
    13

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  19. ➡ Traversable cannot be implemented*
    ➡ Traversable can be detected (instanceof).
    13

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  20. ➡ Traversable cannot be implemented*
    ➡ Traversable can be detected (instanceof).
    ➡ foreach() detects traversable interfaces and
    does magic things.
    13

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  21. 14
    Iterator
    (still not an “spl interface”)

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  22. Userland interface to make
    an object traversable
    15

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  23. 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 )
    }
    16
    Iterator interface:

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  24. 17

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  25. ➡ Iterator
    17

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  26. ➡ Iterator
    ➡ FilterIterators
    17

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  27. ➡ Iterator
    ➡ FilterIterators
    ➡ “Chains” iterators together
    17

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  28. ➡ Iterator
    ➡ FilterIterators
    ➡ “Chains” iterators together
    ➡ IteratorAggregate
    17

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  29. ➡ Iterator
    ➡ FilterIterators
    ➡ “Chains” iterators together
    ➡ IteratorAggregate
    ➡ Is not an iterator, but HAS an iterator
    17

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  30. 1 $dir = opendir(".");
    2 while (($file = readdir($dir)) !== false) {
    3
    4 # Business logic happens here
    5 print "file: $file\n";
    6
    7 }
    18

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  31. 1 $dir = opendir(".");
    2 while (($file = readdir($dir)) !== false) {
    3
    4 # Business logic happens here
    5 print "file: $file\n";
    6
    7 }
    18
    awesome-
    app v1.0

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  32. 1 $dir = opendir(".");
    2 while (($file = readdir($dir)) !== false) {
    3
    4 # hack: filter only mp3 files
    5 if (! preg_match('|\.mp3$|i', $file)) {
    6 continue;
    7 }
    8
    9 # Business logic happens here
    10 print "file: $file\n";
    11 }
    19

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  33. ➡ Filter all MP3 and all JPG files.
    20

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  34. ➡ Filter all MP3 and all JPG files.
    ➡ Filter all MP3 files that are larger than 6MB.
    20

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  35. ➡ Filter all MP3 and all JPG files.
    ➡ Filter all MP3 files that are larger than 6MB.
    ➡ Do not filter at all.
    20

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  36. ➡ 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.
    20

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  37. ➡ 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.
    20

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  38. 21

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  39. ➡ How to test? (we can’t)
    21

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  40. ➡ How to test? (we can’t)
    ➡ How to maintain? (we can’t)
    21

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  41. ➡ How to test? (we can’t)
    ➡ How to maintain? (we can’t)
    ➡ How to reuse? (we can’t)
    21

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  42. 1 $it = new DirectoryIterator(".");
    2 foreach ($it as $fi) {
    3 print "File: ".$fi->getPathname()."\n";
    4 }
    22

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  43. 1 $it = new DirectoryIterator(".");
    2 $it2 = new RegexIterator($it, "/\.mp3$/i");
    3 foreach ($it2 as $fi) {
    4 print "File: ".$fi->getPathname()."\n";
    5 }
    23

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  44. 1 $it = new DirectoryIterator(".");
    2 $it2 = new RegexIterator($it, "/\.mp3$/i");
    3 $it3 = new FilesizeIterator($it2, 0, 6 * 1024 * 1024);
    4 $it4 = new LimitIterator($it3, 5, 3);
    5
    6 foreach ($it4 as $fi) {
    7 print "File: ".$fi->getPathname()."\n";
    8 }
    24

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  45. 1 $it = new DirectoryIterator(".");
    2 $it2 = new RegexIterator($it, "/\.mp3$/i");
    3 $it3 = new FilesizeIterator($it2, 0, 6 * 1024 * 1024);
    4 $it4 = new LimitIterator($it3, 5, 3);
    5
    6 foreach ($it4 as $fi) {
    7 print "File: ".$fi->getPathname()."\n";
    8 }
    24

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  46. 25

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  47. ✓ Reusable
    We can use iterators where ever we want.
    25

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  48. ✓ Reusable
    We can use iterators where ever we want.
    ✓ Testable
    Iterators can be tested separately.
    25

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  49. ✓ Reusable
    We can use iterators where ever we want.
    ✓ Testable
    Iterators can be tested separately.
    ✓ Maintainable
    No need to adapt our business logic.
    25

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  50. 26
    Countable
    (hurrah! An “spl interface”!)

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  51. 1 class myIterator implements \Iterator {
    2 /* ... */
    3 }
    4
    5 $a = array(1, 2, 3);
    6 $it = new myIterator($a);
    7
    8 print count($it);
    27

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  52. 1 class myIterator implements \Iterator {
    2 /* ... */
    3 }
    4
    5 $a = array(1, 2, 3);
    6 $it = new myIterator($a);
    7
    8 print count($it);
    1
    27

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  53. 1 class myCountableIterator extends myIterator implements Countable {
    2 function count() {
    3 return count($this->_elements);
    4 }
    5 }
    6
    7 $a = array(1, 2, 3, 4, 5);
    8 $it = new myCountableIterator($a);
    9
    10 print count($it);
    28

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  54. 1 class myCountableIterator extends myIterator implements Countable {
    2 function count() {
    3 return count($this->_elements);
    4 }
    5 }
    6
    7 $a = array(1, 2, 3, 4, 5);
    8 $it = new myCountableIterator($a);
    9
    10 print count($it);
    5
    28

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  55. 1 class myCountableIterator extends myIterator implements Countable {
    2 function count() {
    3 return count($this->_arr);
    4 }
    5 }
    6
    7 $a = array(1, 2, 3, 4, 5);
    8 $it = new myCountableIterator($a);
    9 $it2 = new limitIterator($it, 0, 3);
    10
    11 print count($it2);
    29

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  56. 1 class myCountableIterator extends myIterator implements Countable {
    2 function count() {
    3 return count($this->_arr);
    4 }
    5 }
    6
    7 $a = array(1, 2, 3, 4, 5);
    8 $it = new myCountableIterator($a);
    9 $it2 = new limitIterator($it, 0, 3);
    10
    11 print count($it2);
    1
    29

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  57. 30
    ITERATORS

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  58. 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
    31

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  59. SPL Iterators
    32
    http://lxr.php.net/xref/PHP_5_5/ext/spl/internal/

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  60. 33

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  61. 34

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  62. ➡ IteratorIterator?
    34

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  63. ➡ IteratorIterator?
    ➡ RecursiveIterator?
    34

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  64. ➡ IteratorIterator?
    ➡ RecursiveIterator?
    ➡ RecursiveIteratorIterator?
    34

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  65. ➡ IteratorIterator?
    ➡ RecursiveIterator?
    ➡ RecursiveIteratorIterator?
    ➡ RecursiveCallbackFilterIterator?
    34

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  66. ➡ IteratorIterator?
    ➡ RecursiveIterator?
    ➡ RecursiveIteratorIterator?
    ➡ RecursiveCallbackFilterIterator?
    34

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  67. 35
    IteratorIterator

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  68. 36
    Turns traversable “things” into an iterator

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  69. 37
    1 $it = new myIterator();
    2 if ($it instanceof \IteratorAggregate) {
    3 $it = $it->getIterator();
    4 }
    5 $it2 = new \LimitIterator($it, 5, 10);

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  70. 38
    1 $it = new myIterator();
    2 $it2 = new \IteratorIterator($it);
    3 $it3 = new \LimitIterator($it2, 5, 10);

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  71. 39
    Recursive*Iterator

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  72. 40
    1 $it = new ArrayIterator(
    2 array("foo", "bar", array("qux", "wox"), "baz"));
    3
    4 foreach ($it as $v) {
    5 print $v . "\n";
    6 }

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  73. 40
    1 $it = new ArrayIterator(
    2 array("foo", "bar", array("qux", "wox"), "baz"));
    3
    4 foreach ($it as $v) {
    5 print $v . "\n";
    6 }
    foo
    bar
    Array
    baz

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  74. 41
    1 $it = new RecursiveArrayIterator(
    2 array("foo", "bar", array("qux", "wox"), "baz"));
    3
    4 foreach ($it as $v) {
    5 print $v . "\n";
    6 }

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  75. 41
    1 $it = new RecursiveArrayIterator(
    2 array("foo", "bar", array("qux", "wox"), "baz"));
    3
    4 foreach ($it as $v) {
    5 print $v . "\n";
    6 }
    foo
    bar
    Array
    baz

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  76. 42
    1 $it = new RecursiveArrayIterator(
    2 array("foo", "bar", array("qux", "wox"), "baz"));
    3 $it2 = new RecursiveIteratorIterator($it);
    4
    5 foreach ($it2 as $v) {
    6 print $v . "\n";
    7 }

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  77. 42
    1 $it = new RecursiveArrayIterator(
    2 array("foo", "bar", array("qux", "wox"), "baz"));
    3 $it2 = new RecursiveIteratorIterator($it);
    4
    5 foreach ($it2 as $v) {
    6 print $v . "\n";
    7 }
    foo
    bar
    qux
    wox
    baz

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  78. 43
    “Recursive” iterators add the POSSIBILITY
    to recursively iterate over data.
    You still need to implement it!

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  79. 44
    RecursiveCallbackFilterIterator

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  80. ➡ Enables recursivity
    ➡ Is a filter iterator (does not necessarily
    return all the elements)
    ➡ Filters through a callback function.
    45

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  81. 46
    SPL Iterators,..

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  82. ➡ It has “quirks” that are easily solvable (but
    breaks BC)
    ➡ Documentation is not always up to date.
    ➡ Naming is VERY confusing (caching
    iterator, recursiveIterator, seekableIterator)
    ➡ But the iterators are worth it!
    47

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  83. 48
    DATA STRUCTURES

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  84. 49
    ➡ SplDoublyLinkedList
    ➡ SplStack
    ➡ SplQueue
    ➡ SplHeap
    ➡ SplMinHeap
    ➡ SplMaxHeap
    ➡ SplPriorityQueue
    ➡ SplFixedArray
    ➡ SplObjectStorage

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  85. 50
    ➡ 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 are quite good!
    ➡ But sometimes other data structures are
    better.

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  86. 51
    PubQuiz

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  87. 52
    http://www.flickr.com/photos/sostark/26697448/

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  88. 52
    http://www.flickr.com/photos/sostark/26697448/
    SplStack

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  89. 53

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  90. 53
    SplQueue

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  91. 54
    http://www.flickr.com/photos/blogchef/4764248456/sizes/z/in/photostream/

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  92. 54
    http://www.flickr.com/photos/blogchef/4764248456/sizes/z/in/photostream/
    Spl(Doubly)LinkedList

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  93. 55
    http://www.flickr.com/photos/pediddle/54326823/

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  94. 55
    http://www.flickr.com/photos/pediddle/54326823/
    SplObjectStorage

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  95. 56

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  96. 56
    SplPriorityQueue

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  97. 57
    http://farm4.static.flickr.com/3224/3072017987_ee454536da.jpg

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  98. 57
    http://farm4.static.flickr.com/3224/3072017987_ee454536da.jpg
    SplHeap

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  99. 58
    http://en.wikipedia.org/wiki/File:USA.NM.VeryLargeArray.02.jpg

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  100. 58
    http://en.wikipedia.org/wiki/File:USA.NM.VeryLargeArray.02.jpg
    SplFixedArray

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  101. 59
    ➡ Use wisely:
    ➡ Don’t use SplStack / SplQueue for
    random reads.
    ➡ Don’t use FixedArrays when you need
    speed boosts.

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  102. 60
    EXCEPTIONS

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  103. ➡ BadFunctionCallException
    ➡ BadMethodCallException
    ➡ DomainException
    ➡ InvalidArgumentException
    ➡ LengthException
    ➡ LogicException
    ➡ OutOfBoundsException
    ➡ OutOfRangeException
    ➡ OverflowException
    ➡ RangeException
    ➡ RuntimeException
    ➡ UnderflowException
    ➡ UnexpectedValueException
    61

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  104. ➡ BadFunctionCallException
    ➡ BadMethodCallException
    ➡ DomainException
    ➡ InvalidArgumentException
    ➡ LengthException
    ➡ OutOfRangeException
    62
    Logic Exceptions Runtime Exceptions
    ➡ OutOfBoundsException
    ➡ OverflowException
    ➡ RangeException
    ➡ UnderflowException
    ➡ UnexpectedValueException

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  105. 63
    1 function foo($str) {
    2 if ($str == "The Spanish Inquisition") {
    3 throw new \UnexpectedValueException("Nobody expects ".$str);
    4 }
    5 /* ... */
    6 }

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  106. 64
    1 function foo($str) {
    2 if ($str == "The Spanish Inquisition") {
    3 throw new \InvalidArgumentException("Nobody expects ".$str);
    4 }
    5 /* ... */
    6 }
    Logic, not runtime

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  107. 65
    1 function foo($str) {
    2 if ($str == "The Spanish Inquisition") {
    3 /* logic */
    4 throw new \InvalidArgumentException("Nobody expects ".$str);
    5 }
    6
    7 try {
    8 $this->getDatabase()->saveRecord($str);
    9 } catch (\RuntimeException $e) {
    10 /* We could try again here */
    11 } catch (\Exception $e) {
    12 /* Sorry, something else occurred. */
    13 }
    14 }

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  108. 66
    Never throw “\Exception”
    Always catch “\Exception”

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  109. 67
    MISC

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  110. ➡ SPL Autoloading
    ➡ SplFileInfo class
    ➡ Spl(Temp)FileObject
    ➡ ArrayObject
    ➡ SplObserver / SplSubject
    68

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  111. 69
    Autoloader

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  112. 70
    spl_autoload_register("spl_autoload_call");

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  113. 70
    spl_autoload_register("spl_autoload_call");
    Throws logicException

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  114. 71
    spl_autoload_unregister("spl_autoload_call");

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  115. 71
    spl_autoload_unregister("spl_autoload_call");
    - Removes ALL the autoloaders!
    - Destroys the autoload stack.
    - Set your house on fire.

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  116. 72
    ArrayObject

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  117. 73
    ArrayObjects are not objects that acts like arrays
    ArrayObjects are objects that acts like arrays

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  118. 74
    1 $a = array("foo", "bar");
    2 $b = $a;
    3 $b[] = "baz";
    4
    5 print_r ($a);
    6 print_r ($b);

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  119. 74
    1 $a = array("foo", "bar");
    2 $b = $a;
    3 $b[] = "baz";
    4
    5 print_r ($a);
    6 print_r ($b);
    Array
    (
    [0] => foo
    [1] => bar
    )
    Array
    (
    [0] => foo
    [1] => bar
    [2] => baz
    )

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  120. 75
    1 $a = new ArrayObject();
    2 $a[] = "foo";
    3 $a[] = "bar";
    4
    5 $b = $a;
    6 $b[] = "baz";
    7
    8 print_r (iterator_to_array($a));
    9 print_r (iterator_to_array($b));

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  121. 75
    1 $a = new ArrayObject();
    2 $a[] = "foo";
    3 $a[] = "bar";
    4
    5 $b = $a;
    6 $b[] = "baz";
    7
    8 print_r (iterator_to_array($a));
    9 print_r (iterator_to_array($b));
    Array
    (
    [0] => foo
    [1] => bar
    [2] => baz
    )
    Array
    (
    [0] => foo
    [1] => bar
    [2] => baz
    )

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  122. 76
    How can we make using the SPL easier?

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  123. 77
    ➡ The (first and only)
    book about the SPL.
    ➡ Written by me (so you
    know it’s good :P)
    ➡ Fixes the
    documentation problem
    of the SPL (or a wobbly
    table)

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  124. 78

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  125. ➡ Adaption of the SPL will only happen
    when developers can become familiar
    with it.
    78

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  126. ➡ Adaption of the SPL will only happen
    when developers can become familiar
    with it.
    ➡ There is currently no real way to
    familiarize yourself with the SPL.
    78

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  127. ➡ BLOG!
    ➡ Update documentation.
    ➡ Find the quirks,
    and maybe even solve them.
    79

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  128. http://farm1.static.flickr.com/73/163450213_18478d3aa6_d.jpg 80

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  129. 81
    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

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