sub mysub (\$var1,$var2)
{ ..code..
 $var1 = "Hello";#this changes $somvar later in the code
}

##</code><code>##

 mysub(my \$somvar,$echo)
 print $somevar

##</code><code>##


sub mysub ()
{ 
 my (\$var1,$var2) = @_;
}
my $somvar = 12;
my $refvar = \$somvar;
mysub($refvar,$echo)
print $somevar