I would like to do this stuff on runtime. Is there documentation about this stuff ?

If you are designing the objects, then look at Class::Prototyped.

   my $cp = Class::Prototyped->new();
    my $mirror = $cp->reflect();
    $mirror->addSlots(
      field1 => 'foo',
      sub1   => sub {
        print "this is sub1 printing field1: '".$_[0]->field1."'\n";
      },
    );

    $mirror->deleteSlot('sub1');
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There are others, too, like Class::Object or Class::Decorator that do things like this in various ways.

If you didn't design the object, then you could use Class::Adapter to wrap the object while adding your own methods.

As more of a hack, if you really need to do it on the fly, you can rebless the object into a dynamically generated subclass that has the methods you want. E.g.

# Create an object of Some::Class
my $obj = Some::Class->new();
$obj->foo();   # where foo() is a method of Some::Class

# Create the new "class" by assigning @ISA and a method in the new nam
+espace
@Some::Class::Extended::ISA = qw/Some::Class/;
*Some::Class::Extended::bar = sub { my $self = shift; print "Hello, Ba
+r" };

# Rebless the object to the new class
bless $obj, 'Some::Class::Extended';

$obj->foo; # From Some::Class
$obj->bar; # From Some::Class::Extended
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