PHP namespaces and dynamic language features-PHP源码-php.cn

PHP namespaces and dynamic language features

伊谢尔伦

Release： 2016-11-23 10:55:37

Original

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PHP 命名空间的实现受到其语言自身的动态特征的影响。因此，如果要将下面的代码转换到命名空间中：

Example #1 动态访问元素

example1.php:

<?php
    class classname
    {
        function __construct()
        {
            echo __METHOD__,"\n";
        }
    }
    function funcname()
    {
        echo __FUNCTION__,"\n";
    }
    const constname = "global";
    $a = &#39;classname&#39;;
    $obj = new $a; // prints classname::__construct
    $b = &#39;funcname&#39;;
    $b(); // prints funcname
    echo constant(&#39;constname&#39;), "\n"; // prints global
?>

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必须使用完全限定名称（包括命名空间前缀的类名称）。注意因为在动态的类名称、函数名称或常量名称中，限定名称和完全限定名称没有区别，因此其前导的反斜杠是不必要的。

Example #2 动态访问命名空间的元素

<?php
    namespace namespacename;
    class classname
    {
        function __construct()
        {
            echo __METHOD__,"\n";
        }
    }
    function funcname()
    {
        echo __FUNCTION__,"\n";
    }
    const constname = "namespaced";
    include &#39;example1.php&#39;;
    $a = &#39;classname&#39;;
    $obj = new $a; // prints classname::__construct
    $b = &#39;funcname&#39;;
    $b(); // prints funcname
    echo constant(&#39;constname&#39;), "\n"; // prints global
    /* 注意如果使用双引号, 一定要使用"\\namespacename\\classname"进行转义 */
    $a = &#39;\namespacename\classname&#39;;
    $obj = new $a; // prints namespacename\classname::__construct
    $a = &#39;namespacename\classname&#39;;
    $obj = new $a; // also prints namespacename\classname::__construct
    $b = &#39;namespacename\funcname&#39;;
    $b(); // prints namespacename\funcname
    $b = &#39;\namespacename\funcname&#39;;
    $b(); // also prints namespacename\funcname
    echo constant(&#39;\namespacename\constname&#39;), "\n"; // prints namespaced
    echo constant(&#39;namespacename\constname&#39;), "\n"; // also prints namespaced
?>

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