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Solution10\ManagedInstance

Managed Instance is a tiny trait that allows you to give classes the ability to manage instances of themselves. This allows you to create singletons, or use them as lazy-DI containers by hot-swapping out instances by name.

Integration

Let's say I have a class called "Auth" that I want to have multiple instances of itself, all of which should be managed through the class.

class Auth
{
    public function login()
    {
        $_SESSION['logged_in'] = true;    
    }
    
    public function logout()
    {
        $_SESSION['logged_in'] = false;
    }
}

NOTE: This is the worst Auth class in the world. Never use it.

To add the ability to manage instances, all I need do is use the managed instance trait:

use Solution10\ManagedInstance\ManagedInstance;

class Auth
{
    use ManagedInstance;

    public function login()
    {
        $_SESSION['logged_in'] = true;    
    }
    
    public function logout()
    {
        $_SESSION['logged_in'] = false;
    }
}

Now I can register instances of my Auth class with the manager.

Registering Instances

Before I can recall an instance, I need to first register it:

$defaultAuth = new Auth();
$defaultAuth->registerInstance(); // Registers this as the 'default' instance

$defaultInstance = Auth::instance(); // Fetches the 'default' instance.

// $defaultAuth === $defaultInstance

$anotherAuth = new Auth();
$anotherAuth->registerInstance('myOtherInstance'); // Registers 'myOtherInstance'

$anotherInstance = Auth::instance('myOtherInstance'); // Returns 'myOtherInstance' instance.

// $anotherAuth === $anotherInstance

As you can see, ManagedInstance does not provide a factory for you. It's up to you to construct and set up the instance before registering it with registerInstance.

You can then get your instances back out with the static instance() method.

Unregistering Instances

I might also want to un-register an instance that has previously been registered. That's not a problem:

$instanceToDelete->unregisterInstance();

Fetching All Instances

You might want to fetch every instance that the class knows about. Not a problem.

$instances = Auth::instances();

This will return a map of each instance with the key as it's name.

Getting/Setting Instance Names

You can also read the name of an instance, or even rename it entirely:

$instance = Auth::instance('myOtherInstance');
echo $instance->instanceName();

// now change it:
$instance->instanceName('mySuperInstance');

// now to read it, you need to do:
$instance2 = Auth::instance('mySuperInstance');