I had a lot of trouble understanding Perl scoping.  After
reading the FAQs, etc, I decided to try writing a program
trying out everything.  Now I think I understand it.

This code consists of a program and a perl module.  They
should be in the same directory.  Run the program.  It
will show how I tried to refer to different declared
variables and subs.

This program uses undeclared package variables
(terminology correct?), 'my' variables, and 'our'
variables.  It doesn't use 'local' variables, though I
might change it.  And it also demonstrates using AUTOLOAD
subs to react to calls to undefined subs.

I really want this to be useful.  So if you see something
I screwed up, or terminology which is wrong, etc, please
tell me.  Thanks! -tim allen

(I) THE PROGRAM (scoping.pl)
#!/usr/bin/perl
# (note: this program will generate a warning if the -w
# command line parameter is used.  This is on purpose
# to show that 'my' causes variables to be lexically scoped
# to their package. -tim)
# Program: scoping.pl
# Purpose: to try out the various ways of referring to variables
# and subs in a package, specifically using "our"
# Author: tim allen
# Restrictions: 1) I don't "use strict" here on purpose so I
#  can have variables not defined as 'my' or 'our'.
#  2) I don't declare anything 'local' -- maybe later.

# The AUTOLOAD sub is special: it catches undefined
# references to subs.  Programming Perl, p. 297
sub AUTOLOAD {
  our $AUTOLOAD;
  warn "$AUTOLOAD NOT DEFINED IN scoping.pl. (AUTOLOAD)\n";
  return undef;
}

sub here_sub {
  my $in_val = shift;
  return "received $in_val in here_sub";
}

use Our_package;

# DEFINITIONS
# define a package variable for *this* package
$package_variable = "defined without 'my' or 'our' in main";
# ... and a lexically scoped variable as well
my $my_variable = "defined with 'my' in main";
# END OF DEFINITIONS

print "VARIABLES IN *THIS* PACKAGE\n";
print "1) \$package_variable=$package_variable\n";
print "2) \$my_variable=$my_variable\n";

print "\nVARIABLE DECLARED IN *OTHER* PACKAGE\n";
print "1) \$our_variable = $our_variable\n" if (defined $our_variable);
print "2) \$our_variable NOT DEFINED\n"   if not (defined $our_variable);
print "3) \$Our_package::our_variable = $Our_package::our_variable\n";
print "4) \$Our_package::my_variable NOT DEFINED\n"
  if not (defined $Our_package::my_variable);

print "\nPACKAGE VARIABLE IN OUTSIDE PACKAGE\n";
print "1) \$package_variable=$package_variable (WRONG)\n";
print "2) \$Our_package::package_variable=$Our_package::package_variable\n";

print "\nCALL SUBROUTINES\n";
print "1) Our_package::our_sub(4) = ".Our_package::our_sub(4)."\n";
print "2) here_sub(4) = ".here_sub(4)."\n";
print "3) here_sub($my_variable) = ".here_sub($my_variable)."\n";

if ($_ = our_sub()) {
  print "our_sub() = ".$_."\n"; 
}

if ($_ = Our_package::our_foo($my_variable)) {
  print "Our_package::our_foo($my_variable) = ".$_."\n";
}

(II) AND NOW THE PERL MODULE (Our_package.pm)
package Our_package;
our $our_variable = "defined with 'our' in Our_package";
$package_variable = "defined without 'my' or 'our' in Our_package";
my $my_variable = "defined with 'my' in Our_package";

sub AUTOLOAD {
  our $AUTOLOAD;
  warn "$AUTOLOAD NOT DEFINED IN Our_package.pm.(Our_package::AUTOLOAD)\n";
  return undef;
}

sub our_sub {
  my $in_val = $_[0];
  return "defined in Our_package (received $in_val)";
}