Giorgio Sironi has a recommendation for developers out there - stop writing foreach loops, there's something better in PHP 5.3+ - closures

There are some array functions which have already been supported at least from Php 4, and that take as an argument a callback whose formal parameters have to be one or two elements of the array. [...] In Php 5.3, callbacks may also be specified as anonymous functions, defined in the middle of other code. These closures are first class citizens, and are treated as you would treat a variable, by passing it around as a method parameter.

He includes some code examples to show you how closures used in callbacks can replace a lot of the other looping normally done by a separate bit of code. Most of the instances are in array functions that take in a callback and apply it to each element in the array (some recursively). The last example shows how to use it in a usort call to make the custom sorting of an array simpler.

Lorna Mitchell has taken a look at using JSON in PHP applications in a new post to her blog. More specifically, she looks at how to get it working and a downfall or two that comes with it.

This is a quick outline on working with JSON from PHP, which is actually pretty simple to do. This post has some examples on how to do it and what the results should look like. JSON stands for JavaScript Object Notation, and is widely used in many languages (not just JavaScript) for serialisation. It is particularly popular for use in web services.

She gives an example of the translation between a PHP array (of subarrays) out into a JSON message complete with grouping. She does mention one problem that using this data format has, though - the lack of typing information that comes along with the message details. That can mean the difference between an array being pushed in on the sending side and an object (from json_decode) coming out the other side. As noted in the comments, though, there's a second parameter for json_decode that tells it to force the output as an array instead (along with a mention of another helpful constant in PHP 5.3 - JSON_FORCE_OBJECT).

In this new post to his blog Stanislav Malyshev looks at creating some Ruby-like iterators as close as they can get in PHP.

I've started playing with Ruby recently, and one of the things that got my attention in Ruby were iterators. They are different inside from regular loops but work in a similar way, and looks like people (at least ones that write tutorials and code examples) like to use them.

He saw how one of the iterators worked - iterating over a Ruby hash - and wondered how difficult it'd be to write up something comparable in PHP. He creates a simple iterator, an array class to lay on top of it and an example of it in use. The use isn't as clean as the Ruby iterator, but it works similarly. He also includes a modification that lets you use ranges for what to return.

Jani Hartikainen has posted a reminder for all developers to filter their incoming data. He points out a specific issue with arrays.

You've written a PHP based web app, and you've made sure it doesn't cause errors if the user submits unexpected values via any URLs or forms. But there's something you quite likely forgot to test: What if the data that's expected to be a singular value happens to be an array? If you assumed a GET or POST parameter will never be an array, your site probably joined the ranks of several high-profile sites that go into funny-mode when given unexpected arrays...

He gives an example exploit of how PHP handles arrays, both in normal PHP and in the Zend Framework, and how those could be interpreted and data could be injected into your script.

In a new post to his blog Brandon Savage takes a look at five different functions for working with arrays you can do some pretty cool things with:

Time and time again, I come across code that contains a variety of array-handling functions that too often duplicate the work that the PHP core team has done to develop built-in array functions. Since the built-in functions are inherently faster, trying to reimplement them in PHP will inevitably be a performance problem.

The five functions he covers are:

• array_key_exists
• usort
• array_pop
• aray_merge
• array_rand

In a recent post Pawel Turlejski takes a look at what he thinks is wrong with PHP closures as compared to syntax in a few other languages.

PHP 5.3, along with many other features, introduced closures. So now we can finally do all the cool stuff that Ruby / Groovy / Scala / any_modern_language guys can do, right? Well, we can, but we probably won't... Here's why.

He compares the PHP syntax for using closures/lambda functions with the abilities of Groovy and Scala. He does point out out that the ArrayObject wrapper does allow you to work a bit more fluently with the array's contents, but it's still not quite the same. According to him:

I'm sure closures will find their uses in the PHP world (like delayed execution or automated resource management), but IMHO replacing traditional loops and array operations is not one of them.

The Standard PHP Library offers PHP developers some excellent tools that, in some cases, can make quite a bit of performance difference than some of their normal counterparts in the rest of the language. In this post from Matt Butcher, two features are compared - normal arrays and the SplObjectStorage feature of the SPL.

One of my projects, QueryPath, performs many tasks that require maintaining a set of unique objects. In my quest to optimize QueryPath, I have been looking into various ways of efficiently storing sets of objects in a way that provides expedient containment checks. [...] Recently I narrowed the list of candidates down to two methods: Use good old fashioned arrays to emulate a hash set or use the SPLObjectStorage system present in PHP 5.2 and up.

He works through the comparison, showing how each of them can emulate the hashed set with the goal of being able to easily iterate and simple to search. The result is that PHP's normal arrays best the SplObjectStorage object in his benchmarking (code included).

Mark van der Velden has posted another PHP quiz you can used to test your knowledge of the language:

A short quiz this time, but that doesn't make it less fun. Do you know the answer to all of them? Get a cup of coffee and kill 10 minutes with round two... As always, think of the answer before you execute the code or look it up. You can find round one here.

This one has questions on arrays, ArrayAccess, references, operator precedence and nesting structures. There's no answer key, so you'll just have to test it out if you want to see the answer.

Ben Scholzen has written up a post about how regular PHP arrays can be used as a native configuration option for your applications.

I was asked many times how I organize my config files, and my response was always the same, until some time ago when I switched began refactoring the codebase of my blog. [...] Looking at [the advantages of PHP config files], you may ask now why not everbody is using them. Well the problem mostly is that you cannot create extend-sections (when working with Zend_Config for example).

He compares an example of a method that, using a base config file with some "smarts", you can have it automatically pull in certain files and overwrite settings from the array inside. A sample "other config" file is also included, showing the definition of some PHP settings, resources and database information.

PHPBuilder.com has posted the seventh part of their "ABCs of PHP" series - a look at arrays and hashes.

An array is a list of a certain variable type, where each item in the list can be referenced by a unique index number, usually starting at 0. [...] Like any other variable type, PHP will automatically define a variable type and set it up for you when you start using it, however in most cases (and it's good practice) you should usually pre-declare your intention to use an array, especially if you don't know in advance what your going to be storing in it.

The article talks about what arrays are, how to create them, manipulating them with functions like array_splice and creating subarrays.