package Foo;
use strict;
use warnings;

sub new {
  my $class = shift;
  $self = bless {@_}, $class;
  $self->init_logging();
}

sub init_logging {
  my $self = shift;
  return if exists $self->{LOGGER};
  eval {
    require SomeLogger;
    $self->{LOGGER} = SomeLogger->new();
  };
}

sub debug {
  my $self = shift;
  return unless exists $self->{LOGGER};
  $self->{LOGGER}->debug(@_);
}

##</code><code>##

my $logger = SomeOtherLogger->new(log_level => 'debug');
my $foo = Foo->new(LOGGER => $logger);

##</code><code>##

use Scalar::Util qw( blessed );
sub debug {
  my $self = shift;
  return unless exists $self->{LOGGER};
  return unless blessed $self->{LOGGER};
  return unless $self->{LOGGER}->can('debug');
  $self->{LOGGER}->debug(@_);
}