#!/usr/bin/perl -w
use strict;

some_sub(1,2);    #called too early warning error
                  #but note that the code still runs!

sub some_sub($$) #this sub requires 2 scalars
{
   my ($a,$b) = @_;
   print "$a,$b\n";
}

some_sub 6,8;      #ok,now this is just fine
some_sub 10,11,12; #too many argument error

__END__
main::some_sub() called too early to check prototype at C:\TEMP\perl33.pl line 6.
1,2

if you reverse order or add proto above call:
sub some_sub($$);
some_sub(1,2);

sub some_sub($$)
{
   my ($a,$b) = @_;
   print "$a,$b\n";
}
Perl will be happy, but to what effect?