#!/usr/bin/env perl
use warnings; use strict;

{ package Basic;
  use warnings; use strict; use mem; use P;
  our @flags;
  use mem (@flags = qw(one two three four five) );
  use Data::Vars \@flags, {one=>1, two=>2, three=>3, four=>4, five=>5};
  sub Decimal() {
    my $p=shift;
    P "\nDecimal:p=%s", $p;

    my $q=__PACKAGE__->new();
    $q->three="change 3 to 33/11";
    P "Decimal: (one, two, three)=(%s, %s, %s)", $q->one, $q->two, $q->three;
  }
}

{ package Derived;
  use warnings; use strict; use mem; use P;
  our @ISA;
  use mem (&{sub() {push @ISA, q(Basic)}});
  use Data::Vars  [qw(one two seven)], 
                  {one=>1.2, two=>2.2, seven=>7.2, eight=>8.2};
  sub new ($) {
    my $p = shift; my $c=$p||ref $p;
    bless $p = Basic->new(@_), $c unless ref $p; 
    $p = $p->Data::Vars::new($p);
  }
  sub Float() {
    my $p=shift;
    P "\nFloat:p=%s", $p;
    
    my $q=__PACKAGE__->new();
    $q->three="Float: 3.3";
    $q->four="Float: Derived 4.4";
    my $val = eval { $q->nine="Float: 9.9"; };
    if ($@) { P "\nassign to nine got:\n%s\n", $@; }
    P "Float:q=%s", $q;
  }
1}


package main;
use warnings; use strict;
use P; use Data::Vars [ qw(one three four) ];

bless my $p = __PACKAGE__->new({one=>'I', three=>'III', four=>'IV'});
P "main:1: p=%s", $p;

$p = Derived->new($p);

P "main:2: %s", $p;

$p->Decimal;
$p->Float;


##</code><code>##


> perl multiuse.pl
main:1: p=main{four=>"IV", one=>'I', three=>"III"}
main:2: Derived{five=>5, four=>"IV", one=>1.20, seven=>7.20, three=>"III", two=>2.20}

Decimal:p=Derived{five=>5, four=>"IV", one=>1.20, seven=>7.20, three=>"III", two=>2.20}
Decimal: (one, two, three)=(1, 2, change 3 to this txt)

Float:p=Derived{five=>5, four=>"IV", one=>1.20, seven=>7.20, three=>"III", two=>2.20}

assign to nine got:
Can't locate object method "nine" via package "Derived" at multiuse.pl line 37.
  eval {...} called at multiuse.pl line 37
  Derived::Float(Derived=HASH(0x8e5648)) called at multiuse.pl line 56

Float:q=Derived{five=>5, four=>"Float: Derived 4.4", one=>1.20, seven=>7.20, three=>"Float: 3.3", two=>2.20}