Kevin Schroeder has a quick new post about using dependency injection in Zend Framework 2 applications using multiple object instances.

When you work with the ZF2 Dependency Injection Container (DiC) when you make multiple requests for an instance of an object you will get the same object back each time. [...] But what if you want the injection benefits of the DiC but don't want to share the object? Use the DiC's newInstance method instead with the third parameter being false.

He includes code examples of requesting the object both ways - the usual way that returns the same object and the alternative that passes in a "false" value, complete with a debug output of each object proving they're different.

In this new post to his blog today Marcelo Gornstein looks at doing some dependency injection in a simple application via XML and YAML configurations and the Ding dependency injection container.

In this past article I've discussed the dependency injection features when using annotations. This time, we'll see how to use the xml and yaml drivers to do the same (setter and constructor injection). If you don't know how to configure the xml and yaml drivers, please start by reading this.

He describes the different injection methods available with the container - setter injection, constructor injection and method injection. Example configuration content is included - both the XML and YAML versions.

Padraic Brady is back today with the second part of his "Dependency Injection in Zend Framework 2.0" series. In this second post he talks about what dependency injection containers are (and aren't) and how they could lead to bad practices if they're considered as service locators.

For Part 2, we're going to dig more into what a DIC is and isn't. I've already noted one very simple DIC called Pimple which will continue as one of my reference points since it best illustrates just how simple a DIC can be. In Part 3, we'll (finally) turn our attention to some actual source code. Baby steps. Parts 1 and 2 should get you thinking so that ZF 2.0′s DIC is a lot easier to understand and critique. We don't want anyone panicking just by throwing them into the deep end.

He talks more about the Pimple DIC tool and how, despite it's similarity to a set of Factory pattern calls, it's slightly different - think of it as "a container of executable Factories". He introduces the concept of a Service Locator, an object that can find and load other objects in an intelligent way. He notes that the most ideal DIC is an "external agent" that defines the object relationships outside of the application.

He points out a feature of ZF2 that allows for injection of the DIC into a controller, allowing it to look up the resources it needs. This of course, has issues - three that he mentions specifically:

• Firstly, this isn't Dependency Injection.
• Secondly, it creates objects which are useless without the specific DIC interface it depends on.
• Thirdly, DICs are really bad Service Locators.