How to use namespace in a Class?

Question

I am using the AWS SDK for PHP by Amazon and for that I need the class S3Client.

I was looking at an example upload to Amazon and did so:

require '../aws/aws-autoloader.php';

use Aws\S3\S3Client;

$s3 = S3Client::factory($config);

Now I’d like to include the S3Client in my class of communication with Amazon (ConnectionCloud). The problem is it makes the following mistake:

PHP Fatal error: Class 'S3client' not found

How do I declare class 'S3client' within my class ConnectionCloud?

Answer 1

Your error is probably in the autoload implementation that is not finding the requested class in the use.

Use the Composer to manage your dependencies and classes when working with PHP namespaces. Since it already includes an autoload that supports community standards, you won’t have major problems working external libraries:

Filing cabinet index.php

<?php

// Autoload do Composer
require 'vendor/autoload.php';

// Instancio uma classe qualquer
$cloud = new MyApp\CloudProvider();

echo $cloud->getProviderClass();

Class CloudProvider.php

<?php namespace MyApp;

// Minha classe está acessando uma biblioteca externa, localizada na pasta vendor
use Aws\S3\S3Client;

class CloudProvider {

    protected $provider;

    public function __construct($config)
    {
        $this->provider = S3Client::factory($config);
    }

    public function getProviderClass()
    {
        return get_class($this->provider);
    }

}

composer.json: composer configuration

{
    "require": {
        "aws/aws-sdk-php": "2.7.*"
    },
    "autoload": {
        "psr-4": { "MyApp\\": "" }
    }
}

Example: https://github.com/gmsantos/namespace

Explanation

To make use of PHP namespaces automatically, without including files via require, we need to implement in PHP a autoload and follow a convention to name our classes and folder structure. In that reply we have a simple autoload implementation.

Note that even in a simple implementation, there is a standard for naming classes. The PHP community adopts some standards with specific rules known as PSR-0 and PSR-4 (more about PSR) to name classes and folders.

In order not to need to implement autoload in all our projects manually, we can use a ready-made implementation. The most used is the Composer, which in addition to being compatible with the above standards, is also a dependency manager.

After installing Composer, just create a file composer.json and within it configure the namespace of your application and the path of your files. It will create a folder vendor in its project, which included the dependencies of its project and a autoload.php ready-to-use.

More information on how to install Composer and use you can find here and also in documentation^en.