Easy Anonymous Objects

On use Perl; the other day revdiablo asked whether there were Anonymous objects as easily as hashrefs? any where within Moose or sitting (hiding!) on CPAN.

Well the answers posted gave a yes for both Moose & CPAN.

Here is my twist on things using something already on CPAN which uses Moose and its Class::MOP foundations: MooseX::SingletonMethod.

With this we can easily create anonymous singleton objects like so:

{
    package Anonyject;
    use MooseX::SingletonMethod;
}

my @dingfirsts;
for my $line ( 1..10 ) {
    push @dingfirsts, Anonyject->new->add_singleton_methods(
        ding => sub { 'ding' x $line },
        dong => sub { 'dong' x $line },
        line => sub { $line },
    )
}

for (@dingfirsts) {
    say "First ", $_->ding, " on line ", $_->line;
}

We can show that each of these objects created have unique anonymous classes using Moose introspection:

for (@dingfirsts) {
    say $_->line, ': ', ( $_->meta->class_precedence_list )[0];
}

# outputs
# => 1: Class::MOP::Class::__ANON__::SERIAL::2
# => 2: Class::MOP::Class::__ANON__::SERIAL::3
# => 3: Class::MOP::Class::__ANON__::SERIAL::4
# => 4: Class::MOP::Class::__ANON__::SERIAL::5
# => 5: Class::MOP::Class::__ANON__::SERIAL::6
# => 6: Class::MOP::Class::__ANON__::SERIAL::7
# => 7: Class::MOP::Class::__ANON__::SERIAL::8
# => 8: Class::MOP::Class::__ANON__::SERIAL::9
# => 9: Class::MOP::Class::__ANON__::SERIAL::10
# => 10: Class::MOP::Class::__ANON__::SERIAL::11

The rest of the class chain upwards for each of these objects is:
Anonyject >> Class::MOP::Class::__ANON__::SERIAL::1 >> Moose::Object

So you can add methods or attributes to Anonyject class and they will be available to all the anonymous objects created.

NB. Class::MOP::Class::__ANON__::SERIAL::1 is where the MooseX::Singleton methods live.

So for more proof in the singleton pudding:

my $obj1 = Anonyject->new->add_singleton_methods(
    ding => sub { "wing" },
    dong => sub { "wong" },
    line => sub { 23_939 },
);

my $obj2 = Anonyject->new->add_singleton_methods(
    something => sub { "else" },
);

say $obj1->ding;      # Says "wing"
say $obj2->something; # Says "else"

say $obj1->something; # Should break and now does
say $obj1->broken;    # Breaks properly
say $obj2->dong;      # And also breaks properly

And all these objects are easily extensible:

# add dingdong just to $obj2 
$obj2->meta->add_method( dingdong => sub { 'dingdong!' } );
say $obj2->dingdong;   # "dingdong!"

# add bang to all anonymous Anonyject objects
Anonyject->meta->add_method( 
    bang => sub { 'bang ' . ( $_[0]->meta->class_precedence_list )[0] } 
);
say $obj1->bang;       # "bang Class::MOP::Class::__ANON__::SERIAL::12"
say $obj2->bang;       # "bang Class::MOP::Class::__ANON__::SERIAL::13"

/I3az/