What does 'dependency injection' solve in PHP? [duplicate]

This question already has answers here: 开发者_Python百科 Closed 11 years ago.

Possible Duplicate:

What is dependency injection?

What is the hipe around 'dependency injection' adapted from Java and introduced in Symfony 2? Could someone give an example of a problem and a solution with and without a dependency injection?

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Explanation that fits to PHP: http://fabien.potencier.org/article/11/what-is-dependency-injection

BTW: It's not from Java world only. DI and variations of DIC are used in most of high level programming languages. It's an universal practice helping you to write more maintanable code.