PHP：变量没有定义

Question

我有这样的代码：

$fm = $app['assetic.filter_manager']; 
$app['assetic.filter_manager'] = $app->share(
    $app->extend('assetic.filter_manager', function($fm, $app) { 
     $fm->set('yui_css', new Assetic\Filter\Yui\CssCompressorFilter(
      '/usr/share/yui-compressor/yui-compressor.jar' 
     )); 
     $fm->set('yui_js', new Assetic\Filter\Yui\JsCompressorFilter(
      '/usr/share/yui-compressor/yui-compressor.jar' 
     )); 

     return $fm; 
    }) 
); 

$app['assetic.asset_manager'] = $app->share(
    $app->extend('assetic.asset_manager', function($am, $app) { 
     $am->set('styles', new Assetic\Asset\AssetCache(
      new Assetic\Asset\GlobAsset(
       __DIR__ . '/assetic/resources/css/*.css', 
//this below is the line 50. 
       array($fm->get('yui_css')) 
      ), 
      new Assetic\Cache\FilesystemCache(__DIR__ . '/assetic/cache') 
     )); 
     $am->get('styles')->setTargetPath('css/styles'); 

     return $am; 
    }) 
); 

我得到这个错误：

PHP Notice: Undefined variable: fm in index.php on line 50 

如果我已经定义的变量$ FM，为什么我收到此错误？

Answer 1

试试这个：

$app->extend('assetic.asset_manager', function($am, $app) use ($fm) { 

Answer 2

如果订单的正确，你声明，并将其设置为不确定的值（$app['assetic.filter_manager']没有设置直到下一行）。

设置$ fm 后赋值。

$app['assetic.filter_manager'] = $app->share(
    $app->extend('assetic.filter_manager', function($fm, $app) { 
     $fm->set('yui_css', new Assetic\Filter\Yui\CssCompressorFilter(
      '/usr/share/yui-compressor/yui-compressor.jar' 
     )); 
     $fm->set('yui_js', new Assetic\Filter\Yui\JsCompressorFilter(
      '/usr/share/yui-compressor/yui-compressor.jar' 
     )); 

     return $fm; 
    }) 
); 

$fm = $app['assetic.filter_manager'];