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SPL to the Rescue - Tek 09


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Given at tek 2009 this is the first version of my SPL to the Rescue talk

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SPL to the Rescue - Tek 09

  1. 1. Standard Tools for Everyday Programming
  2. 2. Community Heckling On twitter #tek09 (or #phptek) and #spldg DG’s for drinking game (you’ll see why later) IRC is open, I can see backlog – constructive criticism is good Comment on No comments on hair, clothes, or my fat belly – constructive criticism is welcome ;)
  3. 3. I have a ProblemRecursively iterate through directoriesFind all .jpg filesCheck last modified datesMoved the ones older than two years to new location
  4. 4. How should I do this? Some nasty recursive use of scandir() to get my lists Or PHP’s dir() function and looping array_map() with a convoluted callbackI think I’m going to need a lot of code….
  5. 5. SPL to the Rescue!  RecursiveDirectoryIterator  RecursiveIteratorIterator  FilterIterator  SplFileInfo What fun tools we have!
  6. 6. And not the kind you kick out of IRC
  7. 7. What is SPL? tandard HP ibrary A library of standard interfaces, classes, and functions designed to solve common programming problems and allow engine overloading.
  8. 8. That’s nice… in English please.What is SPL?1. Engine overloading hooks via interfaces  ArrayAccess, Countable, SeekableIterator2. Classes that utilize the interfaces do cool things  ArrayObject, RecursiveIterator, DirectoryIterator3. Standard Class Implementations  Exceptions, SplObserver and SplStorage4. Functions to help with autoloading and objects  spl_autoload_register(), spl_classes(), iterator_apply()
  9. 9. But… it’s an extension right? SPL is an extension SPL is a core extension SPL cannot be built shared SPL should not be turned off SPL is present in PHP since 5.0 (almost 5 years ago) As of 5.3, SPL cannot be turned off without altering sourceIf you don’t have SPL, whoever built your PHP is an idiot(or an evil genius – it’s HARD).
  10. 10. Helper functions from SPL to you
  11. 11. Autoload Magic spl_autoload() – default autoload implementation spl_autoload_register() – add an autoload to the stack spl_autoload_unregister() – remove an autoloader spl_autoload_functions() – what’s on the stack spl_autoload_extensions() – ext for spl_autoload() spl_autoload_call() – load something through the stack
  12. 12. Isn’t __autoload good enough? Combining different libraries with different naming conventions Dealing with different types of files (templates, classes) in different locations Changing autoload in use during runtime
  13. 13. Object Helper Functions class_implements() class_parents() spl_object_hash()Why are these not in core?I DON’T KNOW - GO ASK YOUR DAD!
  14. 14. Nothing but Templates
  15. 15. Exception Classes LogicExceptionBadFunctionCallE InvalidArgumentE OutofRangeExcept DomainException LengthException xception xception ion BadMethodCall
  16. 16. Exception Classes RuntimeExceptionOutofBoundsExce OverflowExceptio UnderflowExcepti UnexpectedValueE RangeException ption n on xception
  17. 17. So what does SPL offer? A standard set of Exceptions that all inherit from PHP’s Exception base class A standard way to set up exceptions by what kind they are Do I recommend it? Depends on how exceptions are used in your application.
  18. 18. Foreach is your bestest friend! Foreach an object today!
  19. 19. The iterator drinking game! Every time someone says the word iterator tonight, take a drink Start a conversation with me, and you’ll be gone in about five minutes It’s the SPL drinking game (tonight at cocktail hour)
  20. 20. Iterators What the heck is an iterator?  A design pattern that is a generic solution to the problem of iterating over data in a consistent manner.  Access the elements of an aggregate object sequentially without exposing its underlying representation. Why do I care?  Ever need to go over a list of items returned from a database (well, duh)  Or need to go over a list of items returned from a webservice?  Ever used foreach?
  21. 21. Foreach it baby! Foreach is your friend iterators give your code consistent usage and you can add more functionality What else can you do with iterators?  Extend Iterators to do what you need  Chain Iterators: iteratoriteratoriteratoriterator(that’s 5 shots)….
  22. 22. Meet the Iterator Interface
  23. 23. So how is it different?Array $ar= array(); Iterator $it = new Iterator; can be rewound  Might be rewindable  reset($ar)  $it->rewind() is valid unless the key is NULL  should know if there is a value  !is_null(key($ar))  $it->valid() Has a current value  Might have a current value or  current($ar) key Has keys  $it->key()  key($ar)  $it->current() can move forward  Can move forward  next($ar)  $it->next()
  24. 24. An Iterator for every occasion RecursiveIterator • CachingIterator RecursiveIteratorIterator • RecursiveCachingIterator OuterIterator • NoRewindIterator IteratorIterator • AppendIterator FilterIterator • RecursiveIteratorIterator RecursiveFilterIterator • InfiniteIterator ParentIterator • RegexIterator SeekableIterator • RecursiveRegexIterator LimitIterator • EmptyIterator GlobIterator • RecursiveTreeIterator • ArrayIterator
  25. 25. See, the drinking game will be lots of fun….
  26. 26. Innie or an Outie?  OuterIterator (interface)  Extends Iterator  Puts a wrapper around an iterator inside  Has one additional method – getInnerIterator() that should be implemented
  27. 27. Loopety Loop RecursiveIterator (interface)  Has two additional methods to implement  getChildren should return the sub-iterator for the current element – and it must return an object that implements recursiveIterator  hasChildren
  28. 28. Jumping ahead?  SeekableIterator (interface)  Additional method – seek(string $position)  Lets you jump to a specific spot to start iterating
  29. 29. Now on to classes Classes implement interfaces plus provide additional functionality Interfaces need you to fill in all the the required methods You can implement multiple interfaces You can’t extend multiple classesChoose Wisely
  30. 30. FilterIterator Abstract Class Has one method that must be implemented – accept – which should return true or false File filtering example at the beginning used this Highly useful for many types of iteration FilterIterator OuterIterator Iterator Traversable
  31. 31. IteratorIterator Regular Class Iterates an iterator – No I am not kidding IteratorIterator OuterIterator Iterator Traversable
  32. 32. ArrayIterator Regular Class Iterates an array – OR the public properties of an object! (neat trick – dirty trick) ArrayAccess and ArrayIterator SeekableIterator Iterator Traversable Countable too!
  33. 33. RecursiveIteratorIterator Regular Class Like IteratorIterator only recursive to boot – still not kidding - but I don’t say it as cool as Marcus RecursiveIteratorIterator OuterIterator Iterator Traversable
  34. 34. ParentIterator Regular Class Filter out stuff without children ParentIterator OuterIterator Iterator Traversable
  35. 35. LimitIterator Regular Class Like mysql’s limit – pick your range and offset and foreach away! LimitIterator OuterIterator Iterator Traversable
  36. 36. CachingIterator Regular Class Manages another iterator by checking whether it has more elements each time using a hasNext() method CachingIterator OuterIterator Iterator Traversable
  37. 37. RecursiveCachingIterator Regular Class Just like caching iterator only – believe it or not – recursive! RecursiveCachingIterator CachingIterator OuterIterator Iterator Traversable
  38. 38. DirectoryIterator Regular Class Makes going through directories a snap isDot, isFile – I love you SplFileInfo DirectoryIterator Iterator Traversable (extends)
  39. 39. RecursiveDirectoryIterator Regular Class Like, do it again… and again… and again… and… DirectoryIterator RecursiveIterator Iterator Traversable (extends)
  40. 40. Iterator Helper Functions iterator_apply() – like array_walk for your iterator implementing objects iterator_count() – count the items in your iterator (not quite the same as implementing countable::count) iterator_to_array() – copy all the stuff from your iterator into a regular PHP arrayEven Supermandoesn’t work alone
  41. 41. Is it an array? An object? Why… it’s both!
  42. 42. ArrayAccess Interface
  43. 43. ArrayObject A class, NOT an interface It’s like arrayaccess on RedBull The manual LIES – for a full list of everything you can do with arrayobject, see Highlights  exchangeArray  getArrayCopy (get your internally stored array)  Sorting methods  ksort et al
  44. 44. Countable Interface you can implement with any class (not iterator specific, but used a lot for it) Implement the count method and you can use the count() PHP function on any object
  45. 45. SplObjectStorage This does not do what you think it does Use objects as array keys, uniquely, with no collision issues (you might get them from spl_object_hash) Remember you need the object to get the data back out, unless you’re simply iterating over the contents Regular class, no need to extend and fill in methods 2009/34/splobjectstorage-for-a-fa.html
  46. 46. SPLFixedArray A fixed length, int key only array Why? It’s FAST (very fast) because it stores data differently “under the hood” in C Regular class, don’t need to extend and fill in any methods 5.3+
  47. 47. SplObserver and SplSubject Abstract classes for anything using an observer pattern php/2009/02/21/the-observer-pattern/ - great common sense tutorial If you do event/observers in your code, extending these two makes good sense
  48. 48. SplFileInfo fancy class for a file all the file system functions in compact object form  getMTime == filemtime  openFile == fopen
  49. 49. Beyond arrays to the wild wild west
  50. 50. New and Shiny SplDoublyLinkedList SplStack SplQueue
  51. 51. More Data Structures SplHeap SplPriorityQueue SplMaxHeap SplMinHeap
  52. 52. The Documentation Problem phd-on-windows/ - you can write docbook on any platform! Efnet - #php.doc channel – mailing list See me and start helping today!
  53. 53. Resources - spl docs - Doxygen docs reiteration - some stuff about new data structures