monomelodies / disclosure

2.0.2 2016-01-30 11:41 UTC

Requires

• php: >=5.4

Requires (Dev)

• monomelodies/gentry: ^0.5.0

MIT

• Marijn Ophorst

• dependency
• php
• injection

Published on Packagist.org on 2016-01-30 11:49 UTC

README

PHP5 dependency injection and service locator framework. Most existing DI or Inversion of Control (IoC) solutions depend on extensive configuration files to define dependencies. This sucks; Disclosure is better and simpler (we think).

As of version 2.0, Disclosure is fully compatible with the (upcoming) PSR recommendation for Container objects. A copy of the as-yet unrealeased PSR\Container interface is included in the package (until they finally realease it...).

Installation

Composer (recommended)

composer require monomelodies/disclosure

Manual installation

1. Get or clonse the code;
2. Register /path/to/disclosure/src for the namespace Disclosure\\ in your PSR-4 autoloader;
3. Register /path/to/disclosure/psr for the namespace Psr\\Container\\ in your PSR-4 autoloader

Usage

Add your dependencies to a Container object somewhere. It often makes sense to do this in a central file (e.g. src/dependencies.php), but it's also perfectly fine to do it alongside your class definitions.

<?php

use Disclosre\Container;

$container = new Container;
$container->register(function (&$foo, &$bar) {
    $foo = new Foo;
    $bar = new Bar;
});

The container will now assosiate the foo key with an object of instance Foo. The naming of the key is irrelevant; just remember that they must be unique.

Tell your classes what they should depend on using the inject method supplied by the Injector trait:

<?php

use Disclosure\Injector;

class MyClass
{
    use Injector;

    public function __construct()
    {
        $this->inject(function ($foo, $bar) {});
        // Or, alternatively:
        $this->inject('foo', 'bar');
    }
}

class Foo
{
}

$myInstance = new MyClass;
var_dump($myInstance->foo instanceof Foo); // true

inject accepts a random number of arguments, where each argument is their a string with a depedency name, or a callable with dependency names as arguments. Which style you use is up to your own preference.

Whoah! Why not simply do $this->foo = new MyDependency;?

There's plenty of reasons for using a Container instead of the new keyword all over the place, but the main ones are:

• Hard-coding instances makes it hard to inject mocks during unit tests (you could use class_alias for that, but seriously).
• It causes tight coupling between classes, which is a Bad Thing(tm).
• It makes it easier to inject objects as a Service locator (i.e., one instance of an object instead of a new one each time).

No, in the above example it doesn't add much, but see the complete documentation for real-world, practical examples of why dependency injection is generally a good idea.