package Test_logger;

sub new {
    my $pkg = shift;
    my $self = {
        logfile => "/tmp/test_logger.log",  # default
        @_   # merge in user-specified attributes
    };
    open my $fh, ">", $self->{logfile} or die "Cannot open logfile '$self->{logfile}': $!";
    $self->{logfh} = $fh;
    return bless $self, $pkg;
}

sub message {
    my $self = shift;
    my $msg  = shift;
    my $fh = $self->{logfh};
    print $fh "$msg\n";
}

1;

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;

use Test_logger;

sub test_addition {
    my $log = shift;
    $log->message("Inside the subroutine test_addition");
}

my $log = Test_logger->new( logfile => "my.log" );

$log->message("Start of program");

test_addition($log);