Modern-php book excerpt (1) namespace Huawei espace computer version download espace.net patents renault espac

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Namespace

Declaration of namespace

• The namespace is declared at the top of the PHP file, on the first line after the

• The namespace declaration statement begins with It starts with namespace, followed by a space, then the name of the namespace, and finally ends with;;

• The manufacturer namespace, namely "Oreilly" declared below, is the most important namespace; it must be globally unique.

<code><?php
namespace Oreilly;</code>

Subnamespace

<code><?php
namespace Oreilly\ModernPHP;</code>

Ps: All classes, interfaces, and functions under the same namespace do not need to be declared in the same PHP file;
So, we can write the same name in different files Multiple classes of spaces.

import and alias

Before namespace was introduced in PHP, developers used Zend-style class names to solve naming conflicts;

<code># Zend_Cloud_DocumentService_Adapter_WindowsAzure_Query => Zend/Cloud/DocumentService/Adapter/WindowsAzure/Query.php</p>
<p>But as you can see, it’s too long and can’t be tolerated! ! ! <br>namespace provides import and alias to solve this problem. <br>import, alias supports class, interface and namespace import in version 5.3. 5.6 starts to support function and constant import. </p>
<pre class="brush:php;toolbar:false"><code># namespace without alias
<?php
$response = new \Symfony\Component\HttpFoundation\Response('Oops',400);
$response->send();
$response2 = new \Symfony\Component\HttpFoundation\Response('Success',200);</code>

<code># namespace with Default alias 
use Symfony\Component\HttpFoundation\Response;
$response ＝ new Response('Oops',400);
$response->send();</code>

<code># namespace with custom alias 
use Symfony\Component\HttpFoundation\Response as Res;
$response ＝ new Res('Oops',400);
$response->send();</code>

Note:

• Same as the namespace declaration, use the use keyword at the top of the PHP file, and after the

• No need to add a symbol at the beginning, because PHP import is complete Qualification;

• use must appear in the global scope, because use is used at compile time.

PHP5.6 and later can import functions and constants;

<code><?php
use func Namespace\functionName;

functionName();</code>

Import constants:

<code><?php
use constant Namespace\CONST_NAME;

echo CONST_NAME;
</code>

Practical tips

Multiple imports

If you want to import multiple classes, interfaces, functions or constants in a PHP file, you need Use multiple use statements;

Not recommended:

<code><?php
use Symfony\Component\HttpFoundation\Request,
    Symfony\Component\HttpFoundation\Response,
    Symfony\Component\HttpFoundation\Cookie;</code>

Recommended:

<code><?php
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpFoundation\Cookie;</code>

PHP allows one file to define multiple namespaces [Strongly not recommended]

<code><?php
namespace Foo {
    //...
}

namespace Bar {
    //...
}</code>

Global namespace

<code><?php
namespace My\App;

class Foo
{
    public function doSomething()
    {
        $ex = new \Exception();
    }
}</code>

NOTE: At this time, in the Exception class Adding a prefix before the name tells PHP to search for Exception globally. By default, it will search in the current namespace;

The above has introduced the Modern-php book excerpt (1) namespace, including espace and modern aspects. I hope it will be helpful to friends who are interested in PHP tutorials.