Laravel - Contracts

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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.

Every contract defined includes corresponding implementation of the framework. All the Laravel contracts are available in the GitHub repository as mentioned below −

https://github.com/illuminate/contracts

This repository provides a variety of contracts available in the Laravel framework which can be downloaded and used accordingly.

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.

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