On switching, there's a very stylish way to do it in Perl, with which many people aren't familiar. The two are synonyms:

if ($foo =~ /p1/) {
    do1;
} elsif ($foo =~ /p2/) {
    do2;
} elsif ($foo =~ /p3/) {
    do3;
} else {
    do4;
}

SWITCH: for ($foo) {
    /p1/ && do1 && last;
    /p2/ && do2 && last;
    /p3/ && do3 && last;
            do4;
}
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