SPL to the Rescue - Tek 09

Standard Tools for Everyday Programming

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 ;)

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

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….

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

And not the kind you kick out of IRC

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

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()

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).

Helper functions from SPL to you

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

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

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

Nothing but Templates

Exception Classes LogicExceptionBadFunctionCallE InvalidArgumentE OutofRangeExcept DomainException LengthException xception xception ion BadMethodCall

Exception Classes RuntimeExceptionOutofBoundsExce OverflowExceptio UnderflowExcepti UnexpectedValueE RangeException ption n on xception

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.

Foreach is your bestest friend! Foreach an object today!

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)

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?

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)….

Meet the Iterator Interface

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()

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

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

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

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

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

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

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

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

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!

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

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

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

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

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

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

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

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

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

ArrayAccess Interface

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

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

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

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+

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

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

Beyond arrays to the wild wild west

New and Shiny SplDoublyLinkedList SplStack SplQueue

More Data Structures SplHeap SplPriorityQueue SplMaxHeap SplMinHeap

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!

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

SPL to the Rescue - Tek 09

by Elizabeth Smith

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