In this tutorial we’re going to learn what is Contracts and how to using it.

What is Contracts ?

Laravel contracts are a set of interfaces with various functionalities and core services provided by the framework.

For example, Illuminate\Contracts\Queue\Queue contract uses a method which is needed for queuing jobs and Illuminate\Contracts\Mail\Mailer uses the method for sending emails.

Important Points

While working with Laravel contracts, please note the following important points −

• It is mandatory to define facades in the constructor of a class.
• Contracts are explicitly defined in the classes and you need not define the contracts in constructors.

Example

Consider the contract used for Authorization in Laravel which is mentioned below −

<?php

namespace Illuminate\Contracts\Auth\Access;

interface Authorizable{
   /**
      * Determine if the entity has a given ability.
      *
      * @param string $ability
      * @param array|mixed $arguments
      * @return bool
   */
   public function can($ability, $arguments = []);
}

The contract uses a function can which includes a parameter named ability and arguments which uses the user identification in the form of an array.

You will have to define a contract as shown in the syntax below −

interface <contract-name>

Contracts are used like facades for creating robust, well-tested Laravel applications. There are various practical differences with usage of contracts and facades.

The following code shows using a contract for caching a repository −

<?php

namespace App\Orders;
use Illuminate\Contracts\Cache\Repository as Cache;

class Repository{
   /**
      * The cache instance.
   */
   
   protected $cache;
   
   /**
      * Create a new repository instance.
      *
      * @param Cache $cache
      * @return void
   */
   
   public function __construct(Cache $cache) {
      $this->cache = $cache;
   }
}

Contract contains no implementation and new dependencies; it is easy to write an alternative implementation of a specified contract, thus a user can replace cache implementation without modifying any code base.