It will *happen* to work for some invalid inputs. Here are cases that support what I said:

Non-letters in $repl: 

my $find= "find";
my $repl= "@@@@";

$_ = "Find";
print;
s/\b($find)\b/ uc($repl) | ( $1 ^ uc($1) ) /eig;
print;  # @```
        # Should be @@@@

[download]

Non-letters in $find: 

my $find= chr(1234) . 'find';
my $repl= "aaaaa";

$_ = chr(1234) . 'FiNd';
print;
s/\b($find)\b/ uc($repl) | ( $1 ^ uc($1) ) /eig;
print;  # AAaAa
        # Should be aAaAa

[download]

In reply to Re^3: Respect case in substitution by ikegami
in thread Respect case in substitution by b4swine

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