At work I had the task to implement the synchronization between an online shop and a commodity management system. Data exchange format was XML - one big XML file for all of the products (some thousands with dozens of attributes). Big question: How do I import the file in a way that is most convenient for me as a programmer - and without exceeding the machine's RAM when loading a 1 GiB file?

The newer alternatives both use the same technology (DOM and SimpleXML - with DOM behind it) so he goes more "low tech" than that and opts for the XMLReader extension to pull in the large amounts of data. Available in PHP5, the XMLReader extension, which he combines with an Iterator from the SPL to makes for a simple, quick little parser.

Let's kickstart this blogpost by defining what an iterator actually is. According to wikipedia, an iterator is. A collection can pretty much be anything. The most obvious sources would be arrays, but other than that, iterations can be done over database resultsets, strings, datetime intervals, directories, file content and XML listings, to name a few.

He looks at the iterator interface that comes bundled in the SPL and how you can create a custom one to loop through your own data collection. He includes an example - a colorful string iterator that "pretties up" an HTML string with various colors.

When PHP 5 was initially released, it included a strong sense of standardization introduced in the core package. This can be a real time saver when common programming issues must be solved through proven, standard solutions. That's precisely the case with iterators, since the SPL package includes many predefined iterating classes that can be used for traversing different data structures, without having to reinvent the wheel over and over again.

The links include this article on phpro.org and this one on Zend's own site.

Today I will look at the Countable interface, it has a single function that needs to be implemented: count(), by implementing this you can ensure that there is a count() function ready to use on any given class that implements it. The Countable interface is used in other places in the SPL as well: the ArrayIterator and ArrayObject classes implements this interface ( and SqliteResult if present ).

In his code examples he shows simple methods for returning the count() of a property, but notes that the real power of it comes in the ability to manipulate the number returned from the call based on other parameters (or filtering).

This causes a warning in the Quit plugin, which uses exec to automatically detection of the full path to the PHP CLI binary on non-Windows systems that it will later use that path to initiate a new PHP CLI process to "restart" the bot.

It check this setting for the future, it was recommended that he look at the SPL ReflectionFunction class (a part of the Standard PHP Library) that would let him check the disabled status of any PHP function (looking at the result of the isDisabled call).

Operator overloading is a programming language features that allows operators to act differently depending on the type of data they are operating on. Since OOP lets us create custom types (classes), there are plenty of opportunities to do useful and interesting code manipulations using operator overloading.

He talks about magic functions, the additions that the SPL made, the PECL addition operator and how much its currently being discussed on the PHP internals list.

Antony got the idea to implement a C-like array wrapper in SPL: SplFastArray. The main advantage of that class is performance, it's indeed faster than PHP arrays. How so? No free lunch: The speedup comes from the fact that non-numeric indexes are not allowed and that the array is of fixed size.

The code sample shows the setting of the size for the array (and changing it) with a var_dump of the output result. This method is always faster than normal arrays, it just varies how much from system to system (anywhere from ten to thirty percent).

I've been thinking about the Simple Zend_Form File Upload Example that I discussed last month. To recap, if you haven't read the comments, if the form fails to validate for some reason then you get a nasty error.

He corrects the issue by creating an ArrayObject (thanks to the SPL) that can be used both as an array and can look like a string to htmlspecialchars and changing up the validation a little bit to work with the new object.

There finally is documentation for SplDoublyLinkedList, SplStack and SplQueue and some "new" classes: SplHeap (abstract), SplMaxHeap, SplMinHeap and SplPriorityQueue, documentation of those classes is in progress.

An example of the new functionality (for SplPriorityQueue) is included in the post showing the insertion of a value into a pre-existing array (without having to slice or splice!).

It's a generally accepted fact that more readable code is more maintainable and easier for other developers to pick up. [...] Today I'm going to take a look at object iteration, most commonly found in the Standard PHP Library, and explore using the Iterator interface to simplify looping.

The main part of the tutorial shows how to implement the Iterator interface of the SPL to create your own custom methods, theirs being a Database version with methodsfor rewinding, reading and getting the current record you're working with.