Thus the following command is evaluated regardless of filename: 
$error ||= "Unexpected signer 'GOODSIG 86125876138571635 ClientKey' is
+ not ''."
        unless ('GOODSIG 86125876138571635 ClientKey' =~ m/\Q\E/);

[download]
yet sometimes an error is created, sometimes not.

If the error is created, that's because it is set elsewhere. The code you gave will not change $error when $expected_signer is an empty string. That's because m/\Q$foo\E/ will match anything when $foo is empty. (Every string contains an empty string.) In this snippet, $error is only set unless the match is true. Since it is true, $error isn't set.

Update: Changed "Every string matches an empty string" to "Every string contains an emptry string." The latter is what I really meant (as the context implies.) My thanks go to Enlil for spotting it.

-sauoq
"My two cents aren't worth a dime.";

In reply to Re: Regular Expression gotchas ? by sauoq
in thread Regular Expression gotchas ? by the_Don

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