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    <p>Firstly, the DateTime class was a good (tricky) class to choose because it is a horrible class. All of its important work is done in the constructor and there is no way to set the date/time after it has been constructed. This requires us to have an objectGenerator that can build the DateTime object at the correct time. We can still manage this without calling new in the User class though.</p> <p>I have kept things very simple to solve the problem at hand, but they can be extended easily to handle an arbitrarily complex problem.</p> <p>Here is a simple objectGenerator to remove the coupling you get with <code>new</code>.</p> <pre><code> class ObjectGenerator { public function getNew($className) { return new $className; } } </code></pre> <p>Now we inject all of the dependencies into the constructor. The constructor shouldn't do real work, only set up the object.</p> <pre><code>class User { private $phone, $status = 'default', $created, $modified, $pdo, $objectGenerator; public function __construct(PDO $pdo, $objectGenerator) { $this-&gt;pdo = $pdo; $this-&gt;objectGenerator = $objectGenerator; $this-&gt;created = $this-&gt;objectGenerator-&gt;getNew('DateTime'); } public function createNew() { $this-&gt;phone = ''; $this-&gt;status = 'default'; $this-&gt;created = $this-&gt;objectGenerator-&gt;getNew('DateTime'); } public function selectByPhone($phone) { $stmt = $this-&gt;pdo-&gt;prepare('SELECT * FROM `users` WHERE `phone` = :phone'); $stmt-&gt;execute(compact('phone')); if (!$stmt-&gt;rowCount()) { return false; } $record = $stmt-&gt;fetch(PDO::FETCH_ASSOC); $this-&gt;phone = $record['phone']; $this-&gt;status = $record['status']; $this-&gt;created = $record['created']; $this-&gt;modified = $record['modified']; } public function setPhone($phone) { $this-&gt;phone = $phone; } public function setStatus($status) { $this-&gt;status = $status; } public function save() { $stmt = $this-&gt;pdo-&gt;prepare( 'INSERT INTO `users` (`phone`, `status`, `created`, `modified`) VALUES (:phone, :status, :created, :modified) ON DUPLICATE KEY UPDATE `status` = :status, `modified` = :modified'); $modified = $this-&gt;objectGenerator-&gt;getNew('DateTime'); $data = array( 'phone' =&gt; $this-&gt;phone, 'status' =&gt; $this-&gt;status, 'created' =&gt; $this-&gt;created-&gt;format('Y-m-d H:i:s'), 'modified' =&gt; $modified-&gt;format('Y-m-d H:i:s') ); return $stmt-&gt;execute($data); } } </code></pre> <p>Usage:</p> <pre><code>$objectGenerator = new ObjectGenerator(); $pdo = new PDO(); // OR $pdo = $objectGenerator-&gt;getNew('PDO'); $user = new User($pdo, $objectGenerator); $user-&gt;setPhone('123456789'); $user-&gt;save(); $user-&gt;selectByPhone('5555555'); $user-&gt;setPhone('5552222'); $user-&gt;save(); </code></pre> <p>So, <strong>no new or static in the user class</strong>. Try testing both solutions. The test code is a pleasure to write without the calls to new. All classes that use the User will also be easy to test without static calls to it.</p> <p>The differences in test code are:</p> <p><strong>new/static</strong> - Require a stub for each new or static call to stop the unit from reaching outside of itself.</p> <p><strong>dependency injection</strong> - Mock objects can be injected. It is painless.</p>
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    1. PO"Static methods are death to testability" - alternatives for alternative constructors?
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    1. COThanks for your insight. But this now allows the object to easily be put into an inconsistent state. I'm trying to model business rules with the `User` class, which works something like a FSM. The user can only be set into certain states (advance status etc) under certain conditions. Treating it like an Active Record just for the sake of one more abstraction level makes it much harder to enforce that. The static method in this case, as I said, acts as an *alternative constructor*, setting up the internal state from a serialized state.
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    2. COAnd the `DateTime` thing is pretty much the only not injected object. And it's available by default in PHP and has very limited use, there's no need to abstract or mock it IMO.
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    3. COI may have been too liberal with the public interface. It could be replaced with only `createNew` and `selectByPhone`. It does require two lines ($user = new User(); $user->createNew();) to have a valid user, but you are the programmer. You could choose to throw an exception when you try to do something on a user which is not yet valid.
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