use strict;

# you may need to set @INC here (see below)

my @list = qw (J u s t ~ A n o t h e r ~ P e r l ~ H a c k e r !);

#case 1
 use MyModule;
 print func1(@list),"\n";
 print func2(@list),"\n";

# case 2
# use MyModule qw(&func1);
# print func1(@list),"\n";
# print MyModule::func2(@list),"\n";

# case 3
# use MyModule qw(:DEFAULT);
# print func1(@list),"\n";
# print func2(@list),"\n";

# case 4
# use MyModule qw(:Both);
# print func1(@list),"\n";
# print func2(@list),"\n";

-------------------------------------

package MyModule;

use strict;
use Exporter;
use vars qw($VERSION @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS);

$VERSION     = 1.00;
@ISA         = qw(Exporter);
@EXPORT      = ();
@EXPORT_OK   = qw(func1 func2);
%EXPORT_TAGS = ( DEFAULT => [qw(&func1)],
                 Both    => [qw(&func1 &func2)]);

sub func1  { return reverse @_  }
sub func2  { return map{ uc }@_ }

1;
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Case 1 doesn't work because @EXPORT is empty. The symbols in @EXPORT_OK are available for importing but they are not automatically imported.

The tutorial states that Case 1 will generate errors:

Case 1: Because our module exports nothing by default we get errors...

When I run Case 1, I get this error, as expected:

Undefined subroutine &main::func1 called at ...
[download]

Case 3 will also generate an error; Cases 2 and 4 should work properly.