gistfile1.txt

package Foo::Graph;

sub new {
    my $proto = shift;
    my $class = ref($proto) || $proto;
    my $self = {
        template => undef,
    };
    bless( $self, $class );
    #my $template = shift || confess "missing template";
    #$self->{template} = $template;
    $self->{warnings} = [];
    return $self;
}

sub foo() {
    return "abc123";
}

# ======================================

package Foo::ImageGraph;
use base qw( Foo::Graph );

sub new {
    my $proto = shift;
    my $class = ref($proto) || $proto;
    my $self  = $class->SUPER::new(@_);
    bless( $self, $class );
    return $self;
}

# ======================================

package Foo::TimeGraph;
use base qw( Foo::ImageGraph );

sub new {
    my $proto = shift;
    my $class = ref($proto) || $proto;
    my $self  = $class->SUPER::new(@_);
    bless( $self, $class );
    return $self;
}

sub bar {
    my $self = shift;
    #print Dumper( our @ISA );  => Foo::ImageGraph
    print $self->foo();
}

#==============================

package main;
my $obj = Foo::TimeGraph->new;
$obj->bar;