namespaces were implemented from PHP 5.3.0 as a form of "encapsulate items".
I've never really understood his real concept, and I always get confused by class autoload .
Could someone explain me, in a simple way, how namespaces , why they are and if they have something with autoload of classes ?
Example:
namespace App\Http\Controllers; // usando namespace
use App\User; // usando autoload
Namespaces are mostly useful for avoiding name collision.
They were implemented in PHP 5.3.
It is very common to see older PHP libraries using a pattern that uses underline in the class name to avoid conflicts.
This was necessary because, as many libraries were being developed, names began to be "limited" because of collisions of common names.
A great example is to create a class called Client . At least most libraries I've installed on a project have this name. That's where the namespaces come in.
We can see an example of how to solve this problem once.
Example in older versions:
Zend_Server_Client
New versions:
Zend\Server\Client
In versions of PHP 5.6 they become even more useful, since with the new feature of use function , it has become easier to also have a function repository.
Example:
class WallaceMaxters\Helpers;
function print_r($valor)
{
echo '<pre>';
\print_r($valor);
echo '</pre>';
}
This function I created called print_r will not collide with print_r because of the namespace. But to use it in versions prior to php 5.6 , you would have to do something like:
WallaceMaxters\Helpers\print_r($_POST);
Or:
use WallaceMaxters\Helpers as h;
h\print_r($_POST);
But in PHP 5.6, just like the classes, you can create a% local_local for that function.
use function WallaceMaxters\Helpers\print_r as pr
pr($_POST);
Class autoload is a feature added so classes are loaded automatically ( alias and include ) automatically as soon as instantiated.
So, instead of having to include a class to instantiate every time, you simply set a global rule for loading the class.
An example of this is the PSR4 , which I deeply love.
Pattern that is widely used in libraries that can be installed by Composer ;
The standard that most repositories use for their libraries, regarding the use of the namespace is:
NomeDoFornecedor\NomeDaBiblioteca\NomeDaClasse
Example:
namesace Laravel\Database;
class Eloquent {}
Namespaces are used to group items (classes, constants, or functions in php) usually this is determined by the affinity between them. Just as a class groups properties and methods to solve a problem (unique responsibility) with the namescape happens the same however in a larger scope, in other words it defines what the functionalities of that module are.
The php namespace is not as practical as java packs, an advantage would be to load, for example, the entire i18n module that provides classes for formatting dates, currency values, etc., or the persistence module that provides several classes for reading and writing information on different types of technology such as relational database, NOSQL, LDAP etc.
In PHP7 there is a slightly improved way to load a class group
use app\persistencia\{DBRelaciona, DBNoSQL, LDAP};