defunctl/di52

A PHP 5.6+ compatible dependency injection container inspired by Laravel IOC and Pimple that works even better on newer version of PHP.

A quick overview of the Container features:

Auto-wiring - The Container will use Reflection to find what class should be built and how, it's almost magic.
Flexible - Legacy code? Fat constructors with tons of side-effects? The Container offers auto-wiring without making it a requirement. It will adapt to existing code and will not require your code to adapt to it.
Fatal error handling - On PHP 7.0+ the Container will take care of handling fatal errors that might happen at class file load time and handle them.
Fast - The Container is optimized for speed as much as it can be squeezed out of the required PHP compatibility.
Flexible default mode - Singleton (build at most once) an prototype (build new each time) default modes available.
Global Application - Like using App::get($service)->doStuff()? The App facade allows using the DI Container as a globally available Service Locator.
PSR-11 compatible - The container is fully compatible with PSR-11 specification.
Ready for WordPress and other Event-driven frameworks - The container API provides methods like callback and instance to easily be integrated with Event-driven frameworks like WordPress that require hooking callbacks to events.
Service Providers - To keep your code organized, the library provides an advanced Service Provider implementation.

Code Example
Installation
Upgrading from version 2 to version 3
Upgrading from version 3.2 to version 3.3
Quick and dirty introduction to dependency injection
The power of get
Storing variables
Binding implementations
Binding implementations to slugs
Contextual binding
Binding decorator chains
Tagging
The callback method
Service providers
Customizing the container
- Unbound classes resolution
- Exception masking

Code Example

In the application bootstrap file we define how the components will come together:

<?php
/**
 * The application bootstrap file: here the container is provided the minimal set of instructions
 * required to set up the application objects.
 */

namespace lucatume\DI52\Example1;

use lucatume\DI52\App;
use lucatume\DI52\Container;

require_once __DIR__ . '/vendor/autoload.php';

// Start by building an instance of the DI container.
$container = new Container();

// When an instance of `TemplateInterface` is required, build and return an instance
// of `PlainPHPTemplate`; build at most once (singleton).
$container->singleton(
    TemplateInterface::class,
    static function () {
        return new PlainPHPTemplate(__DIR__ . '/templates');
    }
);

// The default application Repository is the Posts one.
// When a class needs an instance of the `RepositoryInterface`, then
// return an instance of the `PostsRepository` class.
$container->bind(RepositoryInterface::class, PostsRepository::class);

// But the Users page should use the Users repository.
$container->when(UsersPageRequest::class)
    ->needs(RepositoryInterface::class)
    ->give(UsersRepository::class);

// Bind primitive values, e.g. public function __construct( int $per_page ) {}
$container->when(UsersPageRequest::class)
    ->needs('$per_page')
    ->give(10);

// Fetch the above class without any further definitions
$container->get(UsersPageRequest::class)

// The `UsersRepository` will require a `DbConnection` instance, that
// should be built at most once (singleton).
$container->singleton(DbConnection::class);

// Set the routes.
$container->bind('home', HomePageRequest::class);
$container->bind('users', UsersPageRequest::class);

// Make the container globally available as a service locator using the App.
App::setContainer($container);

In the application entrypoint, the index.php file, we'll lazily resolve the whole dependency tree following the rules set in the bootstrap file:

<?php
use lucatume\DI52\App;

require_once __DIR__ . '/../../vendor/autoload.php';
require_once __DIR__ . '/bootstrap.php';

$path = parse_url($_SERVER['REQUEST_URI'], PHP_URL_PATH);
$route = basename(basename($path, '.php'), '.html') ?: 'home';

App::get($route)->serve(); ?>
?>

That's it.

Installation

Use Composer to require the library:

composer require lucatume/di52

Include the Composer autoload file in your project entry point and create a new instance of the container to start using it:

<?php
require_once 'vendor/autoload.php';

$container = new lucatume\DI52\Container();

$container->singleton(DbInterface::class, MySqlDb::class);

If you would prefer using the Dependency Injection Container as a globally-available Service Locator, then you can use the lucatume\DI52\App:

<?php
require_once 'vendor/autoload.php';

lucatume\DI52\App::singleton(DbInterface::class, MySqlDb::class);

See the example above for more usage examples.

Upgrading from version 2 to version 3

The main change introduced by version 3.0.0 of the library is dropping compatibility with PHP 5.2 to require a minimum version of PHP 5.6. The library is tested up to PHP 8.1.

If you're using version 2 of DI52 in your project, then there should be nothing you need to do. The new, namespaced, classes of version 3 are aliased to their version 2 correspondent, e.g. tad_DI52_Container is aliased to lucatume\di52\Container and tad_DI52_ServiceProvider is aliased to lucatume\di52\ServiceProvider.

I suggest an update for a small performance gain, though, to use the new, namespaced, class names in place of the PHP 5.2 compatible ones:

replace uses of tad_DI52_Container with lucatume\di52\Container
replace uses of tad_DI52_ServiceProvider with lucatume\DI52\ServiceProvider

The new version implemented PSR-11 compatibility and the main method to get hold of an object instance from the container changed from make to get. Do not worry, the lucatume\di52\Container::make method is still there: it's just an alias of the lucatume\di52\Container::get one. For another small performance gain replace uses of tad_DI52_Container::make with lucatume\di52\Container::get.

That should be all of it.

Upgrading from version 3.2 to version 3.3

Version 3.3.0 of the library removed the aliases.php file, which previously helped to load non-PSR namespaced class names. However, if you're using the tad_DI52_Container and tad_DI52_ServiceProvider classes in your project, you can set up the aliases by adding a few lines of code to your project's bootstrap file to ensure your code continues to work as expected:

<?php

$aliases = [
    ['lucatume\DI52\Container', 'tad_DI52_Container'],
    ['lucatume\DI52\ServiceProvider', 'tad_DI52_ServiceProvider']
];
foreach ($aliases as list($class, $alias)) {
    if (!class_exists($alias)) {
        class_alias($class, $alias);
    }
}

Quick and dirty introduction to dependency injection

What is dependency injection?

A Dependency Injection (DI) Container is a tool meant to make dependency injection possible and easy to manage. Dependencies are specified by a class constructor method via type-hinting:

class A {
    private $b;
    private $c;

    public function __construct(B $b, C $c){
        $this->b = $b;
        $this->c = $c;
    }
}

Any instance of class A depends on implementations of the B and C classes. The "injection" happens when class A dependencies are passed to it, "injected" in its constructor method, in place of being created inside the class itself.

$a = new A(new B(), new C());

The flexibility of type hinting allows injecting into A not just instances of B and C but instances of any class extending the two:

class ExtendedB extends B {}

class ExtendedC extends C {}

$a = new a(new ExtendedB(), new ExtendedC());

PHP allows type hinting not just concrete implementations (classes) but interfaces too:

class A {
    private $b;
    private $c;

    public function __construct(BInterface $b, CInterface $c){
        $this->b = $b;
        $this->c = $c;
    }
}

This extends the possibilities of dependency injection even further and avoids strict coupling of the code:

class B implements BInterface {}

class C implements CInterface {}

$a = new a(new B(), new C());

What is a DI container?

The B and C classes are concrete (as in "you can instance them") implementations of interfaces and while the interfaces might never change the implementations might and should change in the lifecycle of code: that's the Dependency Inversion principle or "depend upon abstractions, non concretions". If the implementation of BInterface changes from B to BetterB then I'd have to update all the code where I'm building instances of A to use BetterB in place of B:

// before
$a = new A(new B(), new C());

//after
$a = new A(new BetterB(), new C());

On smaller code-bases this might prove to be a quick solution but, as the code grows, it will become less and less an applicable solution. Adding classes to the mix proves the point when dependencies start to stack:

class D implements DInterface{
    public function __construct(AInterface $a, CInterface $c){}
}

class E {
    public function __construct(DInterface $d){}
}

$a = new A (new BetterB(), new C());
$d = new D($a, $c);
$e = new E($d);

Another issue with this approach is that classes have to be built immediately to be injected, see $a and $d above to feed $e, with the immediate cost of "eager" instantiation, if $e is never used than the effort put into building it, in terms of time and resources spent by PHP to build $a, $b, $c, $d and finally $e, are wasted. A dependency injection container will take care of building only objects that are needed taking care of resolving nested dependencies.

Need an instance of E? I will build instances of B and C to build an instance of A to build an instance of D to finally build and return an instance of E.

What is a Service Locator?

A "Service Locator" is an object, or function, that will answer to this question made by your code:

$database = $serviceLocator->get('database');

In Plain English "I do not care how it's built or where it comes from, give me the current implementation of the database service.".

Service Locators are, usually, globally-available DI Containers for obvious reasons: the DI Container knows how to build the services the Service Locator will provide when required. The concept of Service Locators and DI Containers are often conflated as a DI Container, when globally available, makes a good implementation of a Service Locator.

An example of this is the lucatume\DI52\App class: it will expose, by means of static methods, a globally-available instance of the lucatume\DI52\Container class.

<?php
use lucatume\DI52\Container;
use lucatume\DI52\App;

// This is a DI Container.
$diContainer = new Container();

// If we make it globally-available, then it will be used by the Service Locator (the `App` class).
App::setContainer($diContainer);

// Register a binding in the DI Container.
$diContainer->singleton('database', MySqlDb::class);

// We can now globally, i.e. anywhere in the code, access the `db` service.
$db = App::get('database');

Since the lucatume\DI52\App class proxies calls to the Container, the example could be made shorter:

<?php
use lucatume\DI52\App;

// Register a binding in the App (Service Locator).
App::singleton('database', MySqlDb::class);

// We can now globally, i.e. anywhere in the code, access the `db` service.
$db = App::get('database');

Construction templates

The container will need to be told, just once, how objects should be built. For the container it's easy to understand that a class type-hinting an instance of the concrete class A will require a new instance of A but loosely coupled code leveraging the use of a DI container will probably type-hint an interface in place of concrete classes. Telling the container what concrete class to instance when a certain interface is requested by an object __construct method is called "binding and implementation to an interface". While dependency injection can be made in other methods too beyond the __construct one that's what di52 supports at the moment; if you want to read more the web is full of good reference material, this article by Fabien Potencier is a very good start.

The power of `get`

At its base the container is a dependency resolution and injection machine: given a class to its get method it will read the class type-hinted dependencies, build them and inject them in the class.

// file ClassThree.php
class ClassThree {
    private $one;
    private $two;

    public function __construct(ClassOne $one, ClassTwo $two){
        $this->one = $one;
        $this->two = $two;
    }
}

// The application bootstrap file
use lucatume\DI52\Container;

$container = new Container();

$three = $container->get('ClassThree');

Keep that in mind while reading the following paragraphs.

Storing variables

In its most basic use case the container can store variables:

use lucatume\DI52\Container;

$container = new Container();

$container->setVar('number', 23);

$number = $container->getVar('number');

Since the container will treat any callable object as a factory (see below) callables have to be protected using the container protect method:

$container = new tad_DI52_Container();

$container->setVar('randomNumberGenerator', $container->protect(function($val){
    return mt_rand(1,100) + 23;
}));

$randomNumberGenerator = $container->getVar('randomNumberGenerator');

The protect method tells the container that, when getting the randomNumberGenerator alias, we do not want to run the function and get its result, but we want to get back the function itself.

Binding implementations

Telling the container what should be built and when is done by an API similar to the one exposed by the Laravel Service container and while the inner workings are different the good idea (kudos to Laravel's creator and maintainers) is reused. Reusing the example above:

use lucatume\DI52\Container;

$container = new Container();

// Bind to a class name.
$container->bind(AInterface::class, A::class);
// Bind to a Closure.
$container->bind(BInterface::class, function(){
    return new BetterB();
});
// Bind to a constructor and methods that should be called on the built object.
$container->bind(CInterface::class, LegacyC::class, ['init','register']);
// Bind to a factory method.
$container->bind(D::interface, [DFactory::class,'buildInstance'])
// Bind to an object, it will be a singleton by default.
$container->bind(E::interface, new EImplementation());

$e = $container->get(F::class);

The get method will build the F object resolving its requirements to the bound implementations when requested. When using the bind method a new instance of the bound implementations will be returned on each request; this might not be the wanted behaviour especially for object costly to build (like a database driver that needs to connect): in that case the singleton method should be used:

use lucatume\DI52\Container;

$container = new Container();

$container->singleton(DBDriverInterface::class, MYSqlDriver::class);
$container->singleton(RepositoryInterface::class, MYSQLRepository::class);

$container->get(RepositoryInterface::class);

Binding an implementation to an interface using the singleton methods tells the container the implementations should be built just the first time: any later call for that same interface should return the same instance. Implementations can be redefined in any moment simple calling the bind or singleton methods again specifying a different implementation.

You can customize how unbound classes are resolved by the container, check the unbound classes section.

Binding implementations to slugs

The container was heavily inspired by Pimple and offers some features of the PHP 5.3+ DI container as well:

use lucatume\DI52\Container;

$container = new Container();

// Storing vars using the ArrayAccess API.
$container['db.name'] = 'appDb';
$container['db.user'] = 'root';
$container['db.pass'] = 'secret';
$container['db.host'] = 'localhost:3306';

// Bindings can be set using ArrayAccess methods.
$container['db.driver'] = MYSQLDriver::class;

// Bound closures will receive the container instance as argument.
$container['db.connection'] = function($container){
    $host = $container['db.host']
    $user = $container['db.user'],
    $pass = $container['db.pass'],
    $name = $container['db.name'],

    $dbDriver = $container['db.driver'];
    $dbDriver->connect($host, $user, $pass, $name);

    return new DBConnection($dbDriver);
};

// Equivalent to $container->get('db.connection');
$dbConnection = $container['db.connection'];

// Using ArrayAccess API to store a closure as a variable.
$container['uniqid'] = $container->protect(function(){
    return uniqid('id', true);
});

There is no replacement for the factory method offered by Pimple: the bind method should be used instead.

Contextual binding

Borrowing an excellent idea from Laravel's container the possibility of contextual binding exists (supporting all the binding possibilities above). Contextual binding solves the problem of different objects requiring different implementations of the same interface (or class, see above):

use lucatume\DI52\Container;

$container = new Container();

/*
 * By default any object requiring an implementation of the `CacheInterface`
 * should be given the same instance of `Array Cache`
 */
$container->singleton(CacheInterface::class, ArrayCache::class);

$container->bind(DbCache::class, function($container){
    $cache = $container->get(CacheInterface::class);
    $dbCache = new DbCache($cache);

    return $dbCache;
});

/*
 * But when an implementation of the `CacheInterface` is requested by
 * `TransactionManager`, then it should be given an instance of `Array Cache`.
 */
$container->when(TransactionManager::class)
    ->needs(CacheInterface::class)
    ->give(DbCache::class);

/*
 * We can also bind primitives where the container doesn't know how to auto-wire
 * them.
 */
$container->when(MysqlOrm:class)
    ->needs('$dbUrl')
    ->give('mysql://user:password@127.0.0.1:3306/app');

/*
 * When primitives are bound to a class the container will correctly resolve them when building the class
 * bound to an interface.
 */
$container->bind(ORMInterface::class, MysqlOrm::class);

// The `ORMInterface` will be resolved an instance of the `MysqlOrm` class, with the `$dbUrl` argument set correctly.
$orm = $container->get(ORMInterface::class);

Binding decorator chains

The Decorator pattern allows extending the functionalities of an implementation without creating an extension and leveraging interfaces. The container allows binding "chain of decorators" to an interface (or slug à la Pimple, or class) using the bindDecorators and singletonDecorators. The two methods are the bind and singleton equivalents for decorators.

use lucatume\DI52\Container;

$container = new Container();

$container->bind(RepositoryInterface::class, PostRepository::class);
$container->bind(CacheInterface::class, ArrayCache::class);
$container->bind(LoggerInterface::class, FileLogger::class);
// Decorators are built left to right, outer decorators are listed first.
$container->bindDecorators(PostEndpoint::class, [
    LoggingEndpoint::class,
    CachingEndpoint::class,
    BaseEndpoint::class
]);

Tagging

Tagging allows grouping similar implementations for the purpose of referencing them by group. Grouping implementations makes sense when, as an example, the same method has to be called on each implementation:

use lucatume\DI52\Container;

$container = new Container();

$container->bind(UnsupportedEndpoint::class, function($container){
    $template = '404';
    $message = 'Nope';
    $redirectAfter = 3;
    $redirectTo = $container->get(HomeEndpoint::class);

    return new UnsupportedEndpoint($template, $message, $redirectAfter, $redirectTo);
});

$container->tag([
    HomeEndpoint::class,
    PostEndpoint::class,
    UnsupportedEndpoint::class,
    ], 'endpoints');

foreach($container->tagged('endpoints') as $endpoint) {
    $endpoint->register();
}

The tag method supports any possibility offered by the container in terms of binding of objects, closures, decorator chains and after-build methods.

The callback method

Some applications require callbacks (or some form of callable) to be returned in specific pieces of code. This is especially the case with WordPress and its event-based architecture . Using the container does not removes that possibility:

use lucatume\DI52\Container;

$container = new Container();

add_filter('some_filter', [$container->get(SomeFilteringClass::class), 'filter']);

This code suffers from an eager instantiation problem: SomeFilteringClass is built for the purpose of binding it but might never be used. The problem is easy to solve using the Container::callback method:

use lucatume\DI52\Container;

$container = new Container();
$container->singleton(SomeFilteringClass::class);

add_filter('some_filter', $container->callback(SomeFilteringClass::class, 'filter'));

The advantage of this solution is the container will return the same callback every time it's called with the same arguments when the called class is a singleton:

// Some code later we need to remove the filter: we'll get the same callback.
remove_filter('some_filter', App::callback(SomeFilteringClass::class, 'filter'));

Service providers

To avoid passing the container instance around ( see Service Locator pattern) or globalising it all the binding should happen in the same PHP file: this could lead, as the application grows, to a thousand lines monster. To avoid that the container supports service providers: those are classes extending the lucatume\DI52\ServiceProvider class, that allow organizing the binding registrations into logical, self-contained and manageable units:

use lucatume\DI52\ServiceProvider;

// file ProviderOne.php
class ProviderOne extends ServiceProvider {
    public function register() {
        $this->container->bind(InterfaceOne::class, ClassOne::class);
        $this->container->bind(InterfaceTwo::class, ClassTwo::class);
        $this->container->singleton(InterfaceThree::class, ClassThree::class);
    }
}

// Application bootstrap file.
use lucatume\DI52\Container;

$container = new Container();

$container->register(ProviderOne::class);
$container->register(ProviderTwo::class);
$container->register(ProviderThree::class);
$container->register(ProviderFour::class);

Booting service providers

The container implements a boot method that will, in turn, call the boot method on any service provider that overloads it. Some applications might define constants and environment variables at "boot" time (e.g. WordPress plugins_loaded action) that might make an immediate registration futile. In that case service providers can overload the boot method:

// file ProviderOne.php

use lucatume\DI52\ServiceProvider;

class ProviderOne extends ServiceProvider {
    public function register() {
        $this->container->bind(InterfaceOne::class, ClassOne::class);
        $this->container->bind(InterfaceTwo::class, ClassTwo::class);
        $this->container->singleton(InterfaceThree::class, ClassThree::class);
    }

    public function boot() {
        if(defined('SOME_CONSTANT')) {
            $this->container->bind(InterfaceFour::class, ClassFour::class);
        } else {
            $this->container->bind(InterfaceFour::class, AnotherClassFour::class);
        }
    }
}

// Application bootstrap file.
use lucatume\DI52\Container;

$container = new Container();

$container->register(ProviderOne::class);
$container->register(ProviderTwo::class);
$container->register(ProviderThree::class);

// Some code later ...
$container->boot();

Deferred service providers

Sometimes even just setting up the implementations might require such an up-front cost to make it undesirable unless it's needed. This might happen with non-autoloading code that will require a tangle of files to load (and side load) to grab a simple class instance. To "defer" that cost service providers can overload the deferred property and the provides method:

// file ProviderOne.php

use lucatume\DI52\ServiceProvider;

class ProviderOne extends ServiceProvider {
    public $deferred = true;

    public function provides() {
        return array(LegacyClassOne::class, LegacyInterfaceTwo::class);
    }

    public function register() {
        include_once('legacy-file-one.php')
        include_once('legacy-file-two.php')

        $db = new Db();

        $details = $db->getDetails();

        $this->container->singleton(LegacyClassOne::class, new LegacyClassOne($details));
        $this->container->bind(LegacyInterfaceTwo::class, new LegacyClassTwo($details));
    }
}

// Application bootstrap file
use lucatume\DI52\Container;

$container = new Container();

// The provider `register` method will not be called immediately...
$container->register(ProviderOne::class);

// ...it will be called here as it provides the binding of `LegacyClassOne`
$legacyOne = $container->get(LegacyClassOne::class);

// Will not be called again here, done already.
$legacyTwo = $container->get(LegacyInterfaceTwo::class);

Dependency injection with service providers

The container supports additional dependency injection for service providers (version 3.0.3+). Auto-wiring will work the same as any class, simply override the service provider's constructor and add any additional concrete dependencies (don't forget to call the parent!):

// file ProviderOne.php

use lucatume\DI52\ServiceProvider;

class ProviderOne extends ServiceProvider {

    /**
     * @var ConfigHelper
     */
    protected $config;

    public function __construct(\lucatume\DI52\Container $container, ConfigHelper $config)
    {
        parent::__construct($container);

        $this->config = $config;
    }

    public function register()
    {
        $this->container->when(ClassFour::class)
            ->needs('$value')
            ->give($this->config->get('value'));
    }

}

// Application bootstrap file.
use lucatume\DI52\Container;

$container = new Container();

$container->register(ProviderOne::class);

If you want to inject primitives into a service provider, you need to utilize the when, needs, give methods before registering the provider in the container:

// file ProviderOne.php

use lucatume\DI52\ServiceProvider;

class ProviderOne extends ServiceProvider {

    /**
     * @var bool
     */
    protected $service_enabled;

    public function __construct(\lucatume\DI52\Container $container, $service_enabled)
    {
        parent::__construct($container);

        $this->service_enabled = $service_enabled;
    }

    public function register()
    {
        if (!$this->service_enabled) {
            return;
        }

        $this->container->bind(InterfaceOne::class, ClassOne::class);
    }

}

// Application bootstrap file.
use lucatume\DI52\Container;

$container = new Container();

$container->when(ProviderOne::class)
    ->needs('$service_enabled')
    ->give(true);

$container->register(ProviderOne::class);

Customizing the container

The container will be built with some opinionated defaults; those are not set in stone and you can customize the container to your needs.

Unbound classes resolution

The container will use reflection to work out the dependencies of an object, and will not require setup when resolving objects with type-hinted object dependencies in the __construct method. By default those unbound classes will be resolved as prototypes, built new on each get request.

To control the mode used to resolve unbound classes, a flag property can be set on the container when constructing it:

use lucatume\DI52\Container;

$container1 = new Container();
$container2 = new Container(true);

// Default resolution of unbound classes is prototype.
assert($container1->get(A::class) !== $container1->get(A::class));
// The second container will resolve unbound classes once, then store them as singletons.
assert($container2->get(A::class) === $container2->get(A::class));

This will only apply to unbound classes! Whatever the flag used to build the container instance, the mode set in the binding phase using Container::bind() or Container::singleton() methods will always be respected.

Exception masking

By default the container will catch any exception thrown during a service resolution and wrap into a ContainerException instance.
The container will modify the exception message and the trace file and line to provide information about the nested resolution tree and point your debug to the file and line that caused the issue.
You can customize how the container will handle exceptions by using the Container::setExceptionMask() method:

use lucatume\DI52\Container;

$container = new Container();

// The container will throw any exception thrown during a service resolution without any modification.
$container->setExceptionMask(Container::EXCEPTION_MASK_NONE);

// Wrap any exception thrown during a service resolution in a `ContainerException` instance, modify the message.
$container->setExceptionMask(Container::EXCEPTION_MASK_MESSAGE);

// Wrap any exception thrown during a service resolution in a `ContainerException` instance, modify the trace file and line.
$container->setExceptionMask(Container::EXCEPTION_MASK_FILE_LINE);

// You can combine the options, this is the default value.
$container->setExceptionMask(Container::EXCEPTION_MASK_MESSAGE | Container::EXCEPTION_MASK_FILE_LINE);

defunctl / di52

Table of Contents

Code Example

Installation

Upgrading from version 2 to version 3

Upgrading from version 3.2 to version 3.3

Quick and dirty introduction to dependency injection

What is dependency injection?

What is a DI container?

What is a Service Locator?

Construction templates

The power of `get`

Storing variables

Binding implementations

Binding implementations to slugs

Contextual binding

Binding decorator chains

Tagging

The callback method

Service providers

Booting service providers

Deferred service providers

Dependency injection with service providers

Customizing the container

Unbound classes resolution

Exception masking

About

Languages

Table of Contents

Code Example

Installation

Upgrading from version 2 to version 3

Upgrading from version 3.2 to version 3.3

Quick and dirty introduction to dependency injection

What is dependency injection?

What is a DI container?

What is a Service Locator?

Construction templates

The power of get

Storing variables

Binding implementations

Binding implementations to slugs

Contextual binding

Binding decorator chains

Tagging

The callback method

Service providers

Booting service providers

Deferred service providers

Dependency injection with service providers

Customizing the container

Unbound classes resolution

Exception masking

About

Languages

The power of `get`