在trigger_error之前，“ @”（沉默运算符，符号处）的作用是什么？ [英] What is the purpose of '@' (silence operator, at sign) before trigger_error?

问题描述

我在许多Symfony捆绑软件（以及其他代码）中都看到以下行：

I have seen in many Symfony bundles (and also in other codes) this line :

@trigger_error('The class is deprecated', E_USER_DEPRECATED);

根据文档， @ （ at）运算符用于使错误静音（ http://php.net/

According to the documentation, the @ (at) operator is used to silence the errors (http://php.net/manual/en/language.operators.errorcontrol.php).

那么，抛出一个沉默错误的目的是什么？

So, what is the purpose of throwing a silenced error?

推荐答案

如 Symfony编码约定：

没有 @-沉默运算符，用户需要退出弃用通知。沉默可以交换这种行为，并允许用户在准备好应对时选择加入（通过添加自定义错误处理程序，例如Web调试工具栏或PHPUnit桥所使用的错误处理程序）。

Without the @-silencing operator, users would need to opt-out from deprecation notices. Silencing swaps this behavior and allows users to opt-in when they are ready to cope with them (by adding a custom error handler like the one used by the Web Debug Toolbar or by the PHPUnit bridge).

评论作者关于相关PR的信息：

Comment from author about the relevant PR:

...还有其他考虑因素使我认为这确实是最好的：性能。我们可以将触发选择弃用通知的实现包装在更多语义接口的后面。但这会增加一些需要尽快处理的开销。当可以调用数千次时，这不是一个微优化。
因此，这种原始的裸金属php实现可能看起来很笨拙，但是恰好满足了我们的需求。

...There is an other consideration that makes me think this is really the best: performance. We could wrap the implementation of triggering "opt-in deprecation notices" behind some more semantic interface. But that would add overhead to something that needs to be as fast as possible. This is not a micro-optim when this can be called thousands of times. Thus this raw-bare-metal-php implementation that may look hacky, but is just the right implementation for our needs.

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