Hm, I'd think that

(?!\w) and (?=\W)

and also

(?<=\w) and (?<!\W)

are equivalent!?

This would unify your "descripted" \b and japhy's "left side boundary".

Also, if it ... flies like a duck, quacks like a duck. .. It probably is a duck?!:

my $rt = [
    [AM => [(qr/\b/) x 2]],
    [japhy1 => [qr/(?:(?=\w)(?<!\w)|(?=\W)(?<!\W))/, qr/(?:(?<=\w)(?!\
+w)|(?<=\W)(?!\W))/]],
    [japhy2 => [qr/(?(?=\w)(?<!\w)|(?<!\W))/, qr/(?(?<=\w)(?!\w)|(?!\W
+))/]],
    [ysth => [(qr/(?:(?=\w)(?<!\w)|(?!\w)(?<=\w))/) x 2]],
];

for my $thing (qw(, th this)) {
    for (@$rt) {
        my $try = $_->[0] . (' ' x (6 - length $_->[0]));    # propose
+r
        my ($lb, $rb) = @{$_->[1]};
        (my $text = "this,that & this, that & this ,that & this , that
+ this")
        =~ s/$lb($thing)$rb/>>$1<</g;
        print "[$try|$thing]$text\n";
    }
}

[download]

Do I have the wrong test cases?

In reply to Re^4: Regex help by pKai
in thread Regex help by Anonymous Monk

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