If your Users module was object oriented, you could simply pass it a reference to a single Error object. Here is how I would handle your example with the Error module:

package Users;

use strict;

sub new {
    my ($class,$error) = @_;
    my $self  = {
        ERRORS => $error,
        # and maybe even more . . . $fh?
    };
    bless $self, $class;
    return $self;
}

sub get_users {
    my ($self,$fh) = shift;
    # rest of your sub

    # oops, an error happened
    $self->{ERRORS}->add_error('oops','i like vb');
}

# rest of your Users module

package main;

use strict;

use Users;
use Error;

my $ERROR = Error->new();
my $user  = Users->new($ERROR);

$user->foo();
print $ERROR->generate_errors();

# or maybe even
my @stuff = $user->foo() or print $ERROR->generate_errors();
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Also, I really should have included this method below in the Error class. I think it's name explains it's function well enough:

package Error;

sub clear {
    my ($self) = @_;
    $self->{ERRORS} = undef;
}

# rest of Error module
[download]

My original requirements didn't warrant the need for that method, but yours just might.

Jeff

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