PHP中实现工厂类模式遭遇命名空间无法正确创建相应的解决代码

参见：PHP手册

Please be aware of FQCN (Full Qualified Class Name) point. 
Many people will have troubles with this: 

<?php 

 // File1.php 
 namespace foo; 

 class Bar { ... } 

 function factory($class) { 
    return new $class; 
} 

// File2.php 
$bar = \foo\factory('Bar'); // Will try to instantiate \Bar, not \foo\Bar 

?>

To fix that, and also incorporate a 2 step namespace resolution, you can check for \ as first char of $class, and if not present, build manually the FQCN: 

<?php 

 // File1.php 
 namespace foo; 

function factory($class) { 
    if ($class[0] != '\\') { 
        echo '->'; 
         $class = '\\' . __NAMESPACE__ . '\\' . $class; 
    } 

    return new $class(); 
} 

 

 

<?php
// File2.php 
$bar = \foo\factory('Bar'); // Will correctly instantiate \foo\Bar 
$bar2 = \foo\factory('\anotherfoo\Bar'); // Wil correctly instantiate \anotherfoo\Bar 
?>