Actually, it's not quit that simple. Perl's standard calling convention isn't pass by value. The values that you get in @_ are aliases to the original variables, so changing @_ will change the values outside the subroutine, as this simple test demonstrates.

my $x = 1;

mult($x);

print "$x\n";

sub mult {
  $_[0] *= 10;
}
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--
<http://www.dave.org.uk>

"Perl makes the fun jobs fun
and the boring jobs bearable" - me