The use Keyword

Part of the Object Oriented Programming section of Coddy's PHP journey — lesson 11 of 91.

Writing the full namespace path every time you use a class can get tedious. The use keyword lets you import a class at the top of your file, so you can reference it by its short name.

Instead of writing \Blog\User repeatedly, you can import it once:

<?php
use Blog\User;

$user = new User("Alice");
echo $user->name;

When you need classes from different namespaces with the same name, you can create an alias using the as keyword:

<?php
use Blog\User as BlogUser;
use Shop\User as ShopUser;

$blogger = new BlogUser("Alice");
$customer = new ShopUser("alice@example.com");

echo $blogger->name . "\n";
echo $customer->email . "\n";

Output:

Alice
alice@example.com

You can also import multiple classes from the same namespace using grouped imports:

<?php
use Blog\{User, Post, Comment};

$user = new User("Alice");
$post = new Post("Hello World");

Key Point: The use statement must appear after the namespace declaration (if any) and before any other code. It makes your code cleaner and easier to read by eliminating repetitive namespace paths.

Challenge

Easy

Let's organize a messaging application using the use keyword to import classes cleanly and avoid writing full namespace paths everywhere.

You'll create three files that work together:

Messaging/Email.php — Define an Email class in the Messaging namespace. It should have a public $address property, a constructor that accepts and sets the address, and a send() method that returns "Sending email to [address]".
Messaging/SMS.php — Define an SMS class in the Messaging namespace. It should have a public $phone property, a constructor that accepts and sets the phone number, and a send() method that returns "Sending SMS to [phone]".
main.php — Include both class files, then use the use keyword to import both classes. Create an Email object with address "alice@example.com" and an SMS object with phone "555-1234". Print the result of calling send() on each object (each on its own line).

In main.php, instead of writing new \Messaging\Email(...), you'll import the classes at the top with use statements so you can simply write new Email(...) and new SMS(...).

Cheat sheet

The use keyword imports a class at the top of your file, allowing you to reference it by its short name instead of the full namespace path:

<?php
use Blog\User;

$user = new User("Alice");

When classes from different namespaces share the same name, create an alias using the as keyword:

<?php
use Blog\User as BlogUser;
use Shop\User as ShopUser;

$blogger = new BlogUser("Alice");
$customer = new ShopUser("alice@example.com");

Import multiple classes from the same namespace using grouped imports:

<?php
use Blog\{User, Post, Comment};

$user = new User("Alice");
$post = new Post("Hello World");

The use statement must appear after the namespace declaration (if any) and before any other code.

Try it yourself

<?php
// Include the class files
require_once 'Messaging/Email.php';
require_once 'Messaging/SMS.php';

// TODO: Use the 'use' keyword to import both classes from the Messaging namespace
// This allows you to write 'new Email(...)' instead of 'new \Messaging\Email(...)'


// TODO: Create an Email object with address "alice@example.com"


// TODO: Create an SMS object with phone "555-1234"


// TODO: Print the result of calling send() on each object (each on its own line)

?>

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

The use Keyword

Cheat sheet

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