Moose::Cookbook::Basics::Recipe7(3p)

NAME
Moose::Cookbook::Basics::Recipe7 - Making Moose fast with immutable

SYNOPSIS
  package Point;
  use Moose;

  has 'x' => ( isa => 'Int', is => 'ro' );
  has 'y' => ( isa => 'Int', is => 'rw' );

  __PACKAGE__->meta->make_immutable;

DESCRIPTION
The Moose metaclass API provides a "make_immutable()" method. Calling this method does two things to your class. First, it makes it faster. In particular, object construction and destruction are effectively "inlined" in your class, and no longer invokes the meta API.

Second, you can no longer make changes via the metaclass API, such as adding attributes. In practice, this won't be a problem, as you rarely need to do this after first loading the class.

CONCLUSION
We strongly recommend you make your classes immutable. It makes your code much faster, with a small compile-time cost. This will be especially noticeable when creating many object.

AUTHOR
Dave Rolsky <autarch@urth.org>

COPYRIGHT AND LICENSE
Copyright 2006-2009 by Infinity Interactive, Inc.

<http://www.iinteractive.com>

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.