PHP:未定义变量

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;
    })
);

我得到了一个错误：

注意:第50行index.php中的未定义变量: fm

如果我已经定义了变量$fm，为什么要得到这个错误？

Answer 1

试试这个：

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

Answer 2

如果该顺序是正确的，则声明它并将其设置为一个未定义的值(直到下一行才设置$app['assetic.filter_manager'])。

在分配之后设置$fm。

$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'];