Dependency injection setters in a base class and having classes requring dependencies as extensions
===

If I'm using setters for dependency injection, and a number of classes all require the same dependencies, should I have all those classes extend a base class with the setters for dependencies in it?

So for example:

Say I have three classes: Page, Article, Comment, all of which depend on $db and $user.

What are the benefits or disadvantages of having a base class Dependencies, something like this:

        class Dependencies
        {
            private $database;
            private $user;
            final public function setDatabase($dbh)
            {
                $this->database = $dbh;
            }

            final public function setUser($user)
            {
                $this->user = $user;
            }
        }

and then having he other classes as extensions of Dependencies

    class Article extends Dependencies
    {
        public function __construct()
        {
            // some code
        }

        // some other functions that use $this->database and $this->user
    }

rather than having setDatabase and setUser exist inside each of the separate classes (Article, Page and Comment).

Thanks.