What is a namespace in PHP? - php

Question

I read an article about namespaces in PHP. But I don't get what they are used for?
<?php
namespace MyProject {
// Regular PHP code goes here, anything goes!
function run()
{
echo 'Running from a namespace!';
}
}
I also read the PHP.net manual about it, but didn't quite get it.

Answer 1

I had a tough time as well, just think of it as a way to help the compiler resolve names.
So there is no ambiguity.
You could have two developers writing completely different classes but with same type identifier.
The class names could be the same. Grouping in namespaces helps the compiler/interpreter will remove the ambiguity.
So namespace Developer1.CoolClass is quite different from namespace Developer2.CoolClass

Answer 2

In the PHP world, namespaces are designed to solve two problems that authors of libraries and applications encounter when creating re-usable code elements such as classes or functions:
Name collisions between code you create, and internal PHP classes/functions/constants or third-party classes/functions/constants.
Ability to alias (or shorten) Extra_Long_Names designed to alleviate the first problem, improving readability of source code.
PHP Namespaces provide a way in which to group related classes, interfaces, functions and constants.
Check Here for details
Namespaces are a way to group your related classes in packages.You can assume namespaces as folders where you keep your files,in a way that both can have the files with same name but different (or same) without any ambiguity.
file1.php
<?php
namespace Foo\Bar\subnamespace;
const FOO = 1;
function foo() {}
class foo
{
static function staticmethod() {}
}
?>
file2.php
<?php
namespace Foo\Bar;
include 'file1.php';
const FOO = 2;
function foo() {}
class foo
{
static function staticmethod() {}
}
/* Unqualified name */
foo(); // resolves to function Foo\Bar\foo
foo::staticmethod(); // resolves to class Foo\Bar\foo, method staticmethod
echo FOO; // resolves to constant Foo\Bar\FOO
/* Qualified name */
subnamespace\foo(); // resolves to function Foo\Bar\subnamespace\foo
subnamespace\foo::staticmethod(); // resolves to class Foo\Bar\subnamespace\foo,
// method staticmethod
echo subnamespace\FOO; // resolves to constant Foo\Bar\subnamespace\FOO
/* Fully qualified name */
\Foo\Bar\foo(); // resolves to function Foo\Bar\foo
\Foo\Bar\foo::staticmethod(); // resolves to class Foo\Bar\foo, method staticmethod
echo \Foo\Bar\FOO; // resolves to constant Foo\Bar\FOO
?>

Answer 3

Consider your write your own class, lets called it Foo. Someone else writes also a part of the project and he calls one of his classes also Foo.
Namespaces solve this problem.
Example:
Namespace MyClasses;
Class Foo
{
}
NameSpace HisClasses;
Class Foo
{
}
$myfoo = new MyClasses\Foo();
$hisfoo = new HisClasses\Foo();

Answer 4

Namespaces are used to isolate functions and class declarations in order to make libraries and "helpers" (files containing functions) more portable. By putting a library in a name space, you reduce the chances of your class names colliding with what an author who may want to use your library may want to call their classes For example, you can have multiple classes named "user" if they're in separate namespaces.