my $switchnum = 15;
my $calltype = []; # Empty array ref
print "ref of switchnum = ref($switchnum) \n
       ref of calltype = ref($calltype) \n";

##</code><code>##

ref of switchnum = ref(15) 

       ref of calltype = ref(ARRAY(0x1234567)) 

##</code><code>##

ref(eval "\$$_") or warn "\$$_ is not a reference" for qw(switchnum calltype);