Win8 Strawberry 5.8.9.5 (32)  Wed 10/28/2020 15:06:58
C:\@Work\Perl\monks
>perl -Mstrict -Mwarnings
my $x;  # undefined/false
my $y = 'default string';

my $side;
if (not $x) { $side = $y; }  # true clause has side effect
# $side = $y unless $x;  # a more terse alternative

printf "side effect '%s'  logical-or '%s'  ternary '%s' \n",
        $side,            ($x || $y),      $x ? $x : $y;
^Z
side effect 'default string'  logical-or 'default string'  ternary 'default string'