The document discusses the Standard PHP Library (SPL) which provides common data structures and interfaces in PHP. It describes various iterator interfaces and classes that can be used to iterate over data in a consistent manner. These include interfaces like Iterator and classes like RecursiveIteratorIterator, FilterIterator, ArrayIterator, DirectoryIterator, and SplFileInfo. It also discusses other SPL components like exceptions, autoloading functions, and data structures.

1. Standard Tools for Everyday Programming

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 http://joind.in/talk/view/186
 No comments on hair, clothes, or my fat belly –
constructive criticism is welcome ;)

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. 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 callback
I think I’m going to need a lot of code….

6. SPL to the Rescue!
 RecursiveDirectoryIterator
 RecursiveIteratorIterator
 FilterIterator
 SplFileInfo
What fun tools we have!

8. And not the kind you kick out of IRC

9. What is SPL?
tandard HP ibrary
A library of standard interfaces,
classes, and functions designed to
solve common programming
problems and allow engine
overloading.

10. That’s nice… in English please.
What is SPL?
1. Engine overloading hooks via interfaces
 ArrayAccess, Countable, SeekableIterator
2. Classes that utilize the interfaces do cool things
 ArrayObject, RecursiveIterator, DirectoryIterator
3. Standard Class Implementations
 Exceptions, SplObserver and SplStorage
4. Functions to help with autoloading and objects
 spl_autoload_register(), spl_classes(), iterator_apply()

11. 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
source
If you don’t have SPL, whoever built your PHP is an idiot
(or an evil genius – it’s HARD).

12. Helper functions from SPL to you

13. 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

14. 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

15. Object Helper Functions
 class_implements()
 class_parents()
 spl_object_hash()
Why are these not in core?
I DON’T KNOW - GO ASK YOUR DAD!

16. Nothing but Templates

17. Exception Classes
LogicException
BadFunctionCallE InvalidArgumentE OutofRangeExcept
DomainException LengthException
xception xception ion
BadMethodCall

18. Exception Classes
RuntimeException
OutofBoundsExce OverflowExceptio UnderflowExcepti UnexpectedValueE
RangeException
ption n on xception

19. 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.

20. Foreach is your bestest friend! Foreach an object today!

21. 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)

22. 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?

23. 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)….

24. Meet the Iterator Interface

25. 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()

26. 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

27. See, the drinking game will be lots of fun….

28. Innie or an Outie?
 OuterIterator (interface)
 Extends Iterator
 Puts a wrapper around an iterator
inside
 Has one additional method –
getInnerIterator() that should be
implemented

29. 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

30. Jumping ahead?
 SeekableIterator
(interface)
 Additional method –
seek(string $position)
 Lets you jump to a
specific spot to start
iterating

31. 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 classes
Choose Wisely

32. 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

33. IteratorIterator
 Regular Class
 Iterates an iterator – No I am not kidding
IteratorIterator OuterIterator Iterator Traversable

34. 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!

35. 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

36. ParentIterator
 Regular Class
 Filter out stuff without children
ParentIterator OuterIterator Iterator Traversable

37. LimitIterator
 Regular Class
 Like mysql’s limit – pick your range and offset and
foreach away!
LimitIterator OuterIterator Iterator Traversable

38. CachingIterator
 Regular Class
 Manages another iterator by checking whether it has
more elements each time using a hasNext() method
CachingIterator OuterIterator Iterator Traversable

39. RecursiveCachingIterator
 Regular Class
 Just like caching iterator only – believe it or not –
recursive!
RecursiveCachingIterator CachingIterator OuterIterator Iterator Traversable

40. DirectoryIterator
 Regular Class
 Makes going through directories a snap
 isDot, isFile – I love you
SplFileInfo
DirectoryIterator Iterator Traversable
(extends)

41. RecursiveDirectoryIterator
 Regular Class
 Like, do it again… and again… and again… and…
DirectoryIterator
RecursiveIterator Iterator Traversable
(extends)

42. 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 array
Even Superman
doesn’t work alone

43. Is it an array? An object? Why… it’s both!

44. ArrayAccess Interface

45. 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
http://www.php.net/~helly/php/ext/spl/
 Highlights
 exchangeArray
 getArrayCopy (get your internally stored array)
 Sorting methods
 ksort et al

46. 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

47. 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
 http://www.colder.ch/news/01-08-
2009/34/splobjectstorage-for-a-fa.html

48. 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+

49. SplObserver and SplSubject
 Abstract classes for anything using an observer pattern
 http://www.a-scripts.com/object-oriented-
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

50. SplFileInfo
 fancy class for a file
 all the file system functions in compact object form
 getMTime == filemtime
 openFile == fopen

51. Beyond arrays to the wild wild west

52. New and Shiny
SplDoublyLinkedList
SplStack SplQueue

53. More Data Structures
SplHeap SplPriorityQueue
SplMaxHeap SplMinHeap

54. The Documentation Problem
 http://elizabethmariesmith.com/2009/02/setting-up-
phd-on-windows/ - you can write docbook on any
platform!
 Efnet - #php.doc channel
 http://doc.php.net
 phpdoc@lists.php.net – mailing list
 See me and start helping today!

55. Resources
 http://php.net/spl - spl docs
 http://php.net/~helly/php/ext/spl - Doxygen docs
 http://blueparabola.com/blog/spl-deserves-some-
reiteration - some stuff about new data structures
 auroraeosrose@php.net