"The downsite is having "magic" numbers in your source code."

One doesn't introduce any new "magic numbers", if instead of writing:

    if (@wishes == 3) {
        print "The genie has granted all of your wishes\n";
    }
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One writes:

    if (3 == @wishes) {
        print "The genie has granted all of your wishes\n";
    }
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        "And the trick only works when comparing against a literal, not a variable."

Granted.  But that doesn't make it any less useful to use for constants, which was my point.

Speaking of magic numbers, I think one can get too carried away with their usage.  I would argue the following goes a bit overboard ...

my $days_per_year = 365;  # In case the number of days in a year chang
+es ;-)
...
if (@calendar < $days_per_year) {
    warn "Hold on, Cinderella -- you're calendar isn't full yet.\n";
}
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The above example is based on a college classmate of mine who, back in the days of BASIC, had the constant "dpy" ("Days per year") in a startup script, so when he needed it, he could type "dpy" instead of "365"!