php教程

User Contributed Notes

Anonymous 10-May-2016 08:15
Tested on PHP 7.0.5, Windows
The line "use animate;" equals the line "use animate as animate;"
but the "use other\animate;" equals "use other\animate as animate;"

file1:
<?php namespace foo;
  class Cat {
    static function says() {echo 'meoow';}  } ?>

file2:
<?php namespace bar;
  class Dog {
    static function says() {echo 'ruff';}  } ?>

file3:
<?php namespace other\animate;
  class Animal {
    static function breathes() {echo 'air';}  } ?>

file4:
<?php namespace fub;
  include 'file1.php';
  include 'file2.php';
  include 'file3.php';
  use foo as feline;
  use bar as canine;
  use other\animate;       //use other\animate as animate;
  echo feline\Cat::says(), "<br />\n";
  echo canine\Dog::says(), "<br />\n";
  echo \animate\Animal::breathes(), "<br />\n";  ?>
varuninorbit at yahoo dot co dot in 27-Dec-2015 06:43
here is a simple example to use namespace

<?php

namespace app\a{
    class one{
       public static function _1(){
        echo 'a one _1<br>';
       }
    }
}

namespace app\b{
    class one{
        public static function _2(){
            echo 'b one _2<br>';
        }
    }
}

namespace app{

    echo a\one::_1();
    echo b\one::_2();
    echo a\two::_1();
}

namespace app\a{
    class two{
       public static function _1(){
        echo 'a two _1<br>';
       }
    }
}

prints
a one _1
b one _2
a two _1
davidkennedy85 at gmail dot com 26-Mar-2015 05:04
In addition to using namespaces and closures, the use keyword has another new meaning as of PHP 5.4 - using traits:

<?php
trait Hello {
    public function sayHello() {
        echo 'Hello ';
    }
}

trait World {
    public function sayWorld() {
        echo 'World';
    }
}

class MyHelloWorld {
    use Hello, World;
    public function sayExclamationMark() {
        echo '!';
    }
}

$o = new MyHelloWorld();
$o->sayHello();
$o->sayWorld();
$o->sayExclamationMark();
?>

More info here: http://php.net/manual/en/language.oop5.traits.php
Ronald W 22-Jan-2015 01:13
<?php
// multiple namespaces in a single file:

namespace foo{
  class Cat {
    static function says() {echo 'meoow';}  }
}

namespace bar{
  class Dog {
    static function says() {echo 'ruff';}  } 
  class Cat {
    static function says() {echo 'meowi';}  }
  class Mouse {     //nonstatic function
    function says() {echo 'Come and get me ;)';}  }
}

namespace animate{
  class Animal {
    static function breathes() {echo 'air';}  }
}

namespace{        // No Namespace: global code
  use foo as feline;
  use bar as canine;
  use bar\Mouse as MouseOnly;
  use animate;
  echo animate\Animal::breathes(), "<br />\n"; 
  echo feline\Cat::says(), "<br />\n"; //not starting with a slash!
  echo canine\Cat::says(), "<br />\n";
  echo canine\Dog::says(), "<br />\n";
  //any of the three following lines work:
  // $micky=new bar\Mouse();
  // $micky=new canine\Mouse();
  $micky=new test();
  echo $micky->says();
}
?>
Anonymous 25-May-2011 11:06
The keyword 'use' has two different applications, but the reserved word table links to here.

It can apply to namespace constucts:

file1:
<?php namespace foo;
  class Cat {
    static function says() {echo 'meoow';}  } ?>

file2:
<?php namespace bar;
  class Dog {
    static function says() {echo 'ruff';}  } ?>

file3:
<?php namespace animate;
  class Animal {
    static function breathes() {echo 'air';}  } ?>

file4:
<?php namespace fub;
  include 'file1.php';
  include 'file2.php';
  include 'file3.php';
  use foo as feline;
  use bar as canine;
  use animate;
  echo \feline\Cat::says(), "<br />\n";
  echo \canine\Dog::says(), "<br />\n";
  echo \animate\Animal::breathes(), "<br />\n";  ?>

Note that
felineCat::says()
should be
\feline\Cat::says()
(and similar for the others)
but this comment form deletes the backslash (why???)

The 'use' keyword also applies to closure constructs:

<?php function getTotal($products_costs, $tax)
    {
        $total = 0.00;
       
        $callback =
            function ($pricePerItem) use ($tax, &$total)
            {
               
                $total += $pricePerItem * ($tax + 1.0);
            };
       
        array_walk($products_costs, $callback);
        return round($total, 2);
    }
?>

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