Black Friday Black Friday
Black Friday ultimate sale! Get up to 80 % extra free points! More information here

Lesson 6 - Passing dependencies with Dependency Injection

Software design Software architectures and dependency injection Passing dependencies with Dependency Injection

In the previous lesson, Wrong ways of passing dependencies - Singleton and SL, we completed a walk through the wrong ways of passing dependencies in multi-tier applications. Overall, it was about using any static class members, including Singleton, but also about passing dependencies through a container, known as the Service Locator pattern, or different variations of these approaches. Today, we're gonna show how to do it right on our car example as always.

Laborious ways

So far, the only right way we know is to pass dependencies manually one by one. This is also the approach we showed at the very beginning of the course. We created a database instance in index.php and passed it to the controller and through the controller to the model where it was needed. Although this approach is correct from the software-design point of view, you can certainly imagine how much work it would take to pass several dependencies like this even in a medium-sized application. And since controllers are created automatically by the router, we 'd also need to identify which dependencies should be passed to which controller. Last time, I promised I would stop bothering you with the wrong solutions and questions any more. Today's lessons will bring answers to everything. Really :)

What was wrong?

In all the presented solutions, we tried to hack the code so we didn't have to pass dependencies. This CANNOT be achieved without negative impacts. All such attempts will always result in failures. If we don't pass


 

...End of the preview...

Premium article

Premium article

ict.social is a large database made up of manuals and tutorials, whose main goal is to provide high-quality IT education to everyone. We started out in the Czech republic, where we display roughly a million articles per month and receive plenty of gratitude from our users. Thanks to our successful establishment, we are now bringing these articles to the rest of the world.

Although we are trying to keep our content free of charge, maintaining the site is a huge effort for everyone involved. Therefore, some content (exercises and more advanced material) costs network points. Don't worry, they're really cheap :)

Article description

Requested article covers this content:

This tutorial explains what we did wrong till now, what Inversion of Control is and how the Dependency Injection pattern works in practice.

Buy just this article

To access the article, you need 16 points
Currently, you have 0 points
You gain 16 points for adding an article to the site, or for $1.44

Buying this article gives you unlimited access to it forever. You will learn some more and help us keep giving our site maintenance which helps you and others get better futures. It's a win-win.

This article is licensed :Premium II, by buying this article, you agree with the terms of use.

You gain points by supporting our network. This is done by sending a helpful amount of money to support the site, or by creating content for the network.

You can get points immediately using:

Credit card SMS Wire transfer
Credit card SMS Wire transfer

 

Article has been written for you by David Capka
Avatar
The author is a programmer, who likes web technologies and being the lead/chief article writer at ICT.social. He shares his knowledge with the community and is always looking to improve. He believes that anyone can do what they set their mind to.
Unicorn College The author learned IT at the Unicorn College - a prestigious college providing education on IT and economics.
Activities (5)