Devious! ;)

The most devious part is japhy's innocuous comment. $(...) syntax is hogwash!

The $ starts the regex engine matching at the end of the string. Since $` is the portion preceding the current match, it gets set to the entire contents of $_.

Now the (??{code}) zero-width assertion comes into play. $` >= $X is evaluated (as a string) and its result inserted into the regex. In Perl, boolean values stringify to "1" or "".

So if $_ < $X, the comparison fails (returning ""), so the regex is simply /$/, which always succeeds. Otherwise, the comparison succeeds (returning "1"), and the regex is (equivalent to) qr'$1', which can never succeed.

blokhead

In reply to Re: Is $_ less than $X by blokhead
in thread Is $_ less than $X by japhy

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