Namespace in PHP. Code example

Namespaces allow you to avoid name conflicts and group functionality. Within a namespace there can be
classes, interfaces, functions and constants are placed.

Creating a namespace

To create a namespace, use the namespace directive followed by the namespace name:

<?php
namespace base;//create namespace

//everything below the namespace belongs to it
class Person
{
    private $name;
    function __construct($name) { 
        $this->name = $name; 
    }
}

?>

Appeal to the namespace

A special construction /namespace/Classname is used to refer to the namespace:

$tom = new \base\Person("Victor");

In your projects, we recommend using the /App/Classname structure to name projects. Accordingly, the class should be in the app folder.

Appeals from another class

file.php code example:

namespace base;

class Person
{
    public $name;
    function __construct($name) { $this->name = $name; }
}

Now, in another file, we include this file and refer to the Person class:

    namespace work;
    
    include "Person.php";
    $tom = new \base\Person("Tom");
    echo $tom->name;

Some namespaces can contain others:

namespace base\classes;

Aliases

Calling classes with their namespaces makes our code harder to read and cumbersome.

In this case, we can use aliases, which are given in the form:

use full_classname_with_namespaces as pseudonym;

<?php
namespace work;
include "person.php";
 
use \base\classes\Person as User;
 
$tom = new User("Tom");

$bob = new User("Bob");

?>

You can only use the use construct without specifying an alias. Then the class can be used according to its
direct name:

use \base\classes\Person;

$tom = new Person("Tom");
$bob = new Person("Bob");

Several classes at once:

use \base\classes\Person as User, \base\classes\Employee as Employee;


use \base\classes\{Person as User, Employee as Employee};

Connecting Constants and Functions

The const statement is used to connect constants, and “use function” is used to connect functions.

//create namespace
namespace base\classes;


const admin = "Garry";


function printPerson($person){
     
    echo $person->name;
}

class Person {
    public $name;
    function __construct($name) { 
        $this->name = $name; 
    }
}

Connect this file to another:

//in this file we have another namespace
namespace work;
include "admin.php";
 
//allow you to use the Person class in this file with others namespace
use \base\classes\Person;
//allow to use the admin constant without specifying namespaces
use const \base\classes\admin;
//allow to use function printPerson without specifying namespaces
use function \base\classes\printPerson;
 
$tom = new Person(adminName);
printPerson($evan);  
?>