Building on several recent threads on inside-out objects, I've recently released an "alpha" version of a simple, safe and streamlined toolkit for building inside-out objects called Class::InsideOut.

Compared to other inside-out object building modules already on CPAN, this module aims for minimalism and robustness:

• Does not need to be subclassed

• No source filters

• No attributes or CHECK blocks

• Doesn't leak memory

• Overload-safe

• Thread-safe (for Perl 5.8 or better)

• Supports any underlying object-type, including direct foreign inheritance

• Has hooks for Storable to serialize scalar, array or hash-based inside-out objects

The goal of Class::InsideOut is to provide the minimal support necessary for creating safe inside-out objects. All other implementation details, including writing a constructor and managing inheritance, are left to the user. More advanced builders could be written on top of Class::InsideOut, of course.

For example, here is a very simple class:

package My::Class;

use Class::InsideOut qw( property register id );

# declare a lexical property hash with 'my'
property my %name; 

sub new {
    my $class = shift;
    my $self = \do {my $scalar};
    bless $self, $class;

    # register the object for thread-safety
    register( $self ); 
}

sub get_name {
    my $self = shift;
    
    # optional 'id' as alias to Scalar::Util::refaddr
    return $name{ id $self };
}

1; # modules must be true
[download]

For a more complete description of the philosophy, design, and interface, please see the Class::InsideOut documentation. The documentation includes a comparison to other inside-out object generators on CPAN. Of the various modules, the one that is closest to this is Object::InsideOut, which I recommend for a more full-featured approach.

(At the risk of straining a simile, perhaps, Class::InsideOut is supposed to be like a Honda Civic -- basic and dependable. Object::InsideOut is more like a Porsche -- designed for speed and style. I see the two as complements, not competitors.)

As the basic inside-out feature set is working and code-coverage is high, Class::InsideOut needs some field testing. I encourage fellow monks to download it, give it a test drive and offer some feedback. To those with enough expertise to find implementation weaknesses, I would particularly welcome your insights. (In particular, I'd greatly appreciate if someone could give it a spin under mod_perl and some Storable-compatible session manager, as I don't have an environment for those handy to test.)

Thanks!