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  • 位置: php7教程 -> php7语言

    php7命名空间

    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);
      }
    ?>
    
    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"; ?>
    
    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
    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
    <?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();
    }
    ?>