Symfony 4服务别名

要澄清此示例中“@”的用法:“@sonata.page.twig.extension”

没有它,你就告诉容器传递字符串 奏鸣曲.page.twig.extension .
有了它,你就告诉集装箱通过服务 奏鸣曲.page.twig.extension .

从文档中,请参阅代码中的以下注释: https://symfony.com/doc/current/service_container.html

 # explicitly configure the service
    App\Service\MessageGenerator:
        arguments:
            # the '@' symbol is important: that's what tells the container
            # you want to pass the *service* whose id is 'monolog.logger.request',
            # and not just the *string* 'monolog.logger.request'
            $logger: '@monolog.logger.request'

好的解决方案

  Sonata\PageBundle\Twig\Extension\PageExtension:
    alias: 'sonata.page.twig.extension'
    public: true

为什么有时@sonata.page.twig.extension有时sonata.page.twig.extension