http://qs321.pair.com?node_id=768428
Description: This piece of code may serve as the base class for objects that need singleton methods (methods specific for this object and not for whole class). One can use it directly
my $obj = DynObject->new(id => 'MyObj', action => sub{print "hi\n";}); print $obj->id, "\n"; $obj->action();
or as base class
$obj = MyDyn->new(id => 'MyObj'); print $obj->id, "\n"; $obj->action(); package MyDyn; use base 'DynObject'; sub action { print "hi\n"; }
use strict;
package DynObject;
use Carp;

my $counter = 0;

sub new
{
    my $class = shift;
    croak("The number of parameters must be even") unless @_ % 2 == 0;

    no strict 'refs';
    my $type = ref $class;
    my $code;
    if(!$type)
    {
        $type = __PACKAGE__;
        $type .= "::obj@{[$counter++]}";
        *{"${type}::ISA"} = [$class];
    }
    for(my $i = 0; $i < @_; $i+=2)
    {
        croak("The method name '$_[$i]' is not a word")
            unless $_[$i] =~ /^\w+$/ && $_[$i] !~ /^\d+$/;
        if(ref $_[$i+1] eq 'CODE')
        {
            *{"${type}::$_[$i]"} = $_[$i+1];
        }
        elsif(defined $_[$i+1] && !ref $_[$i+1])
        {
            my $str = $_[$i+1];
            *{"${type}::$_[$i]"} = sub{$str};
        }
        else
        {
            delete ${"${type}::"}{$_[$i]};
        }
    }
    return ref $class ? $class : bless [], $type;
}

sub DESTROY
{
    my $obj = shift;
    my $type = ref $obj;
    $type =~ s/(\w+)$//;
    my $name = $1 . "::";
    no strict 'refs';
    delete ${$type}{$name};
}

1;