Dependency Injection
Reinventing how you manage
PHP classes
PHP classes
This book is about Symfony Dependency Injection, a PHP library part of the Symfony Components project. Its official website is at http://components.symfony-project.org/dependency_injection/.
About the Symfony Components
Symfony Components are standalone PHP classes that can be easily used in any PHP project. Most of the time, they have been developed as part of the Symfony framework, and decoupled from the main framework later on. You don't need to use the Symfony MVC framework to use the components.
Symfony Dependency Injection is a PHP library that provides a lightweight and robust Dependency Injection Container for classes that implement the Dependency Injection pattern.
Dependency Injection is a best practice to follow if you want to easily reuse your classes and provides an elegant way to facilitate unit testing.
A Dependency Injection Container manages object instantiation and configuration for you.
If you are interested in learning more about Dependency Injection, you can read the Martin Fowler introduction or the excellent Jeff More presentation. You can also have a look at a presentation I gave on Dependency Injection, where I talk in more detail on the exact same example as the one used in this book.
One of the goals of Symfony Dependency Injection is to be as fast as possible. With the possibility to dump any container to a plain PHP file, you can use the library without any overhead whatsoever, certified.
Released under the MIT license, you are free to do whatever you want, even in a commercial environment. You are also encouraged to contribute.
Symfony Dependency Injection has its roots in the great Spring framework. But instead of being a straight port of a Java container, the library has been rethought and redesigned to take into account the PHP platform specificities.
There is only one archive to download, and you are ready to go. No configuration, and no installation. Drop the files in a directory and start using it today in your projects.
Thanks to the great flexibility of the library, Symfony Dependency Injection comes bundled with a Graphviz dumper, allowing you to visualize the graph of your objects and ease the debugging of your container.
Symfony Dependency Injection is one of the fundamental libraries behind the Symfony 2 framework. It is also used by many other big "enterprise-like" projects.
Symfony Dependency Injection is fully documented, with a dedicated online book, and of course a full API documentation.
The library is fully unit-tested. With 100% code coverage, the library is stable and ready to be used in large projects.
Symfony Dependency Injection is flexible enough for all your needs, even the most complex ones. Thanks to an open architecture, you can implement your own dumpers and loaders (by default, it comes with full support for XML, YAML, PHP, INI, and Graphviz).
Symfony Dependency Injection can be installed by downloading the source code as a tar archive or a zip one.
To stay up-to-date, you can also use the official Subversion repository.
If you are a Git user, there is an official mirror, which is updated every 10 minutes.
If you prefer to install the component globally on your machine, you can use the symfony PEAR channel server.
Support questions and enhancements can be discussed on the mailing-list.
If you find a bug, you can create a ticket at the symfony trac under the dependency_ _injection component.
The Symfony Dependency Container component is licensed under the MIT license:
Copyright (c) 2008-2009 Fabien Potencier
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
If you find a typo or an error, please
register
and open a ticket.
If you need support or have a technical question, please post to the official
Symfony Components mailing-list.
