Here's one way (requires 5.10+). You'll decide for yourself if it is any better:

sub test{ 
    my $p1 = shift // 1; 
    my $p2 = shift // 2; 
    my $p3 = shift // 3; 
    print "p1:$p1; p2:$p2; p3:$p3";
};;

test();;
p1:1; p2:2; p3:3

test( 'a' );;
p1:a; p2:2; p3:3

test( 'a', 'b' );;
p1:a; p2:b; p3:3

test( 'a', 'b', 'c' );;
p1:a; p2:b; p3:c
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