myFirstObject.pm

package pieChart {
  use Moose;

  has 'label', is => 'ro', isa => 'Str';
  has 'data',  is => 'ro', isa => 'ArrayRef';
  has 'pcsuccess', is => 'ro', isa => 'Int';
  has 'pcerror',   is => 'ro', isa => 'Int';

  sub png {
    use GD::Graph::pie;

    my $self = shift;
    my $chart = GD::Graph::pie->new();
    my $colors = [qw/green red/];
    my $catego = [qw/success error/];
    my $data;

    if (defined $self->data) {
      $data = $self->data;
    } else {
      $data = [$self->pcsuccess,$self->pcerror];
    }

    my @pie = ($catego,$data);

    $chart->set(dclrs => $colors,
		title => "% of SUCCESS(".uc($self->label).")");

    $chart->plot(\@pie);

    open IMG,">",$self->label.".png" or die $!;
    binmode IMG;
    print IMG $chart->gd->png;
    close IMG;
  }

  return 1;
}

using_my_first_oject.pl

#! /usr/bin/perl -w

use strict;
use warnings;
use feature 'say';
use myFirstObject;

my $data = [55,45];
my $name = "mon super gros essai";
my $test = pieChart->new(label => $name,data => $data);
$test->png or die "Unable to create PNG chart : $!";

my $essai = pieChart->new(label => 'second test', pcsuccess => 62,
			  pcerror => 28);
$essai->png or die "Unable to create PNG chart : $!";