I've found the module MooseX::Role::Flyweight a useful one for keeping a cache of objects, but I've never been happy with the way it requires you to use Class->instance(y => 'x') instead of Class->new(y => 'x') to get the new object. What if I change my mind about caching, or want to debug the code without the cache? Then I have to find all the calls in all my code and change them. What if I miss one, and call new from outside the class? So much for the cache.

I came up with this alternative approach, which seems to work. It overrides Moose's new method but still inlines the constructor.

package TestNew 0.001;

use Moose;

has thingy => (
    required => 1,
    is       => 'ro',
);

my %obj_cache;

override 'new' => sub {
    my ( $class, @args ) = @_;
    my $params   = $class->BUILDARGS(@args); # from Moose::Object
    my $thingy   = $params->{thingy};
    my $cachekey = $thingy;
    if ( exists $obj_cache{$cachekey} ) {
        return $obj_cache{$cachekey};
    }
    return $obj_cache{$thingy} = $class->_new( thingy => $thingy );
};

*Moose::Object::_new = \&Moose::Object::new;

__PACKAGE__->meta->make_immutable( constructor_name => '_new' );

1;
[download]

Other than the unfortunate need to mess around inside the Moose::Object namespace, I don't see any huge downsides, but I must admit I don't really know what I'm looking at when I poke around inside Class::MOP::Class and was wondering if others had thoughts.

Thanks,