php命名空间和动态语言特征

<?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
?>

<?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
?>