That could be better written as 
print join ',', @boxes;

[download]
unless you're concerned about the joined string being enormous, in which case I'd probably say 
my $printed = 0;
foreach my $box ( @boxes ) {
    print ',' if $printed++;
    print $box;
}

[download]
But your code is perfectly safe. The alternatives are only evaluated if the corresponding condition indicates that they should be.
Caution: Contents may have been coded under pressure.

In reply to Re^2: order of arguments evaluated by Roy Johnson
in thread order of arguments evaluated by Anonymous Monk

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