sminnee/app-rfc.md

## app-rfc.md

      
    Raw
  

              app-rfc.md
            
          
    Problem

There are a few issues with the current SilverStripe 4 code:

Our bootstrap is a large pile of spaghetti. This makes it harder to build other scripts that pull in SilverStripe services.
There are a lot of top-level anchors of global state - Injector::inst(), Config::inst(), etc, that need to managed. This is especially clear in the case of test execution
We're increasingly using Injector, and combined with fully-qualified interface/class names as the service names, makes sonme

These issues could be solved with an App object
The App object

namespace SilverStripe\Core;

class App
{

    // singleton management
    static function inst();
    static function set_inst(App $inst);

    // Core objects that make up a SilverStripe application
    function getModuleManifest();
    function getConfig();
    function getInjector();

    // Shortcut for $this->getInjector()->get("$service.$namespace");
    function getService($service, $namespace = null);

    // Shortcuts for key services from the injector
    function getDatabase($namespace = null);
    function getCache($namespace = null);
    function getDirector();
}
The App object would be instantiated in bootstrap. As well as getters for the 3 core services (module manifest, config, and injector), it can be a staging ground for other shortcut methods.
DefaultAppFactory

Rather than a lengthy sequential bootstrap, we can refactor the bootstrap code to be a factory. That way, the boostrap could be as simple as something like this:
require_once __DIR__ . '../vendor/autoload.php';

use SilverStripe\Core\DefaultAppFactory;
use SilverStripe\Control\DefaultRequestFactory;

$app = DefaultAppFactory::create();
$request = DefaultRequestFactory::create();
$response = $app->getDirector()->direct($request);
$response->output();

inst()

The current inst() methods scattered in the app can be refactored to defer state management to App:
class Injector {
  function inst() {
    reutrn App::inst()->getInjector();
  }
}
This means that tests can be boostrapped by putting in a new App object.
$this->App

Any object that is instantiated by the injector can be configured to have an $app property populated with the relevant object.
This means we can encourage developers to avoid static calls to app/injector/etc altogether!
class SomeClass {
  function someCustomThing {
    $cache = $this->app->getService(SimpleCache::class);
    return $this->app->getDatabase()->query("SELECT * FROM CustomTable")->first();
  }
}