What is the purpose of '@' (silence operator, at sign) before trigger_error?

Question

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

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

Accor

Answer 1

Adding to what other people said, according to the docs this entire scheme boils down to the following example:

set_error_handler(function ($errno, $errstr) {
    var_dump($errstr); // outputs "Will only be seen ..."
}, E_USER_DEPRECATED);

@trigger_error('Will only be seen from a custom error handler', E_USER_DEPRECATED);

Otherwise put, a silenced deprecation notice still can be heard from a custom error handler, if needed, not polluting the usual logs in the same time.