(Re)discovering the SPL - PHPWorld

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1 Joshua Thijssen jaytaph (Re)discovering the SPL

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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 Q: Have you ever used the SPL?

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

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5 SPL Documentation

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

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➡ Not enough documentation. 8

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➡ Not enough documentation. ➡ Very few examples. 8

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

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

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

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11 INTERFACES

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12 Traversable (not an “spl interface”)

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➡ Traversable cannot be implemented* 13

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

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

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14 Iterator (still not an “spl interface”)

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Userland interface to make an object traversable 15

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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 ) } 16 Iterator interface:

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➡ Iterator 17

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➡ Iterator ➡ FilterIterators 17

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➡ Iterator ➡ FilterIterators ➡ “Chains” iterators together 17

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

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

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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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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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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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➡ Filter all MP3 and all JPG files. 20

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

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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. 20

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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. 20

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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. 20

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➡ How to test? (we can’t) 21

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

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

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

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

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

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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. 25

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

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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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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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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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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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30 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 31

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

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➡ IteratorIterator? 34

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➡ IteratorIterator? ➡ RecursiveIterator? 34

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➡ IteratorIterator? ➡ RecursiveIterator? ➡ RecursiveIteratorIterator? 34

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➡ IteratorIterator? ➡ RecursiveIterator? ➡ RecursiveIteratorIterator? ➡ RecursiveCallbackFilterIterator? 34

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➡ IteratorIterator? ➡ RecursiveIterator? ➡ RecursiveIteratorIterator? ➡ RecursiveCallbackFilterIterator? 34

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35 IteratorIterator

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36 Turns traversable “things” into an iterator

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

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39 Recursive*Iterator

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

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44 RecursiveCallbackFilterIterator

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

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46 SPL Iterators,..

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➡ 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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48 DATA STRUCTURES

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

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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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51 PubQuiz

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

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

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53 SplQueue

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

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

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

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

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56 SplPriorityQueue

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

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

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

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

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

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60 EXCEPTIONS

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

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

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

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67 MISC

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

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69 Autoloader

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70 spl_autoload_register("spl_autoload_call");

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70 spl_autoload_register("spl_autoload_call"); Throws logicException

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71 spl_autoload_unregister("spl_autoload_call");

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

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72 ArrayObject

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

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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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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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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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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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76 How can we make using the SPL easier?

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

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

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

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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