You really want || there as the = binds tighter than the or e.g 
perl -MO=Deparse -
my @things = $q->param('t') or $q->param('things');
my @things = $q->param('t') || $q->param('things');
^D

$q->param('things') unless my(@things) = $q->param('t');
my(@things) = $q->param('t') || $q->param('things');

[download]
Your best option for conditionally assigning lists is the ternary conditional operator e.g 
my @things = $q->param('t') ? $q->param('t') : $q->param('things');

[download]
HTH

_________
broquaint

In reply to Re: Precendence and wantarray puzzling me by broquaint
in thread Precendence and wantarray puzzling me by ViceRaid

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