Rob Allen has a new post to his blog today introducing you to the ZendEventManager component of the Zend Framework v2, a key part of how this latest version of the framework does its job.

Zend Framework 2's EventManager is a key component of the framework which is used for the core MVC system. The EventManager allows a class to publish events that other objects can listen for and then act when the event occurs. The convention within Zend Framework 2 is that any class that triggers events composing its own EventManager.

He starts with some terminology to get everyone on the same page (listener, event, EventManager) and includes an example of its use in setting up a "PhotoMapper" object showing how to trigger events in the "findById" method. He shows how to listen for a specific event (in his case, a "pre-execute" on the "findById" method) and a method for "short circuiting" the listener based on the response from the "trigger" call. He also touches on the "SharedEventManager" that can be used to add an event across all of your application at the same time.

Following up on their previous look at the component architecture of the Yii framework, PHPMaster has posted this new tutorial showing how the framework allows you to do some event-based programming.

An application event is something that occurs which might be of interest to other bits of code. A standard event in most GUI applications would be a "click" event, but the sky's the limit and what events you define is really up to you. [...] The details can be provided by application-specific modules allowing you to keep individual requirements separate from your reusable code. Events allow you to attach a potentially unlimited amount of functionality without changing your core modules and components.

In his example, he shows how to create an event handler that is triggered when the user registers on the site. This event (CEvent) is then registered with the system and is attached via a call in the controller's "init" method.

On the Zend Developer Zone, a recently posted tutorial looks at fetching multiple random rows from a database table (in a MySQL database).

As a follow up to my earlier article about fetching a single random row from MySQL I will tell you today, how you can fetch multiple random rows from a table without any hassle. Compared to the solution with fetching a single random row, fetching multiple random rows requires some tricks.

The tutorial walks you through the creation of some sample tables, making a simple trigger to keep a "random ID" column in a value range of one to the number of rows (gapless) and a bit of PHP code to select some IDs from the table and the SQL to get their information.

Be sure to check out the comments for mentions of the number of table reads and how optimized certain parts of the queries might be.

On DevShed today, there's this new tutorial aimed at more advanced PHP developers concerning how to simulate events in PHP5.

PHP has the drawback of not supporting events. Fortunately, a basic structure can be built to support events in PHP 5. This article tackles that problem with some proof of concept code.

It seemed reasonable to me that some sort of basic structure could be established to support events in PHP 5, so I set out to whip something up as quickly as possible as a proof of concept. The contents of this article are the work of roughly one programming hour and surely stand to be improved upon, but the basic idea is this: instantiate an object and attach event handlers; the handlers will be executed when the events they are associated with are raised.

They look first at how to create a simple object to store the information in and a "collection" class to manage those objects. They move on to the creation of the event handler class and a "collection" class for handling those as well. Finally, they get to the combination of the above items - a class that does an eval on the inputted string and creates an associative array.