Re^2: Bug or feature? s/// and the g option

Interesting. So a failed match will clear the $1 variable. I'm still a little stumped by Marco's original example:

$test = <<'END';
XXWY
XXWZ
END

$count = $test =~ s#(XXW?Y)##gi;
print "REMOVED: <<$1>>\nCOUNT: $count\n";
[download]

That fails. But remove the "i" in the substitution and $1 is defined. Why would case-insensitive make any difference?
--rjk

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Re^3: Bug or feature? s/// and the g option by ysth (Canon) on Oct 14, 2007 at 19:46 UTC
AIUI, without the i, before the regex engine proper is entered, there's an optimization that makes it search for an XX followed later by a Y. That optimization rejects a match, and when that happens, it bypasses the bug that's setting $1 to undef. Seems to be fixed for 5.10.0.	[reply]
Re^4: Bug or feature? s/// and the g option by Belgarion (Chaplain) on Oct 14, 2007 at 20:14 UTC
Ah, thanks for the explanation ysth! --rjk	[reply]