my $value = shift() || 'default';

##</code><code>##

my $value = shift() or 'default';

##</code><code>##

my $value = shift() || 'default';

##</code><code>##

my $value = shift() or 'default';

##</code><code>##

#temp.pl
$value = $x or $y or $z;
$value = $x || $y || $z;
$value = $x or $y || $z;
$value = $x || $y or $z;

##</code><code>##

perl -MO=Deparse,-p  temp.pl

##</code><code>##

((($value = $x) or $y) or $z);
($value = (($x || $y) || $z));
(($value = $x) or ($y or $z));
(($value = ($x || $y)) or $z);
temp.pl syntax OK

##</code><code>##

$value = $x or $y or $z;

##</code><code>##

$value = $x or $y || $z;

##</code><code>##

 
$value = $x || $y or $z;