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.IX Title "Moose::Cookbook::Basics::Immutable 3"
.TH Moose::Cookbook::Basics::Immutable 3 2026-06-15 "perl v5.42.2" "User Contributed Perl Documentation"
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.SH NAME
Moose::Cookbook::Basics::Immutable \- Making Moose fast by making your class immutable
.SH VERSION
.IX Header "VERSION"
version 2.4000
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 2
\&  package Point;
\&  use Moose;
\&
\&  has \*(Aqx\*(Aq => ( isa => \*(AqInt\*(Aq, is => \*(Aqro\*(Aq );
\&  has \*(Aqy\*(Aq => ( isa => \*(AqInt\*(Aq, is => \*(Aqrw\*(Aq );
\&
\&  _\|_PACKAGE_\|_\->meta\->make_immutable;
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
The Moose metaclass API provides a \f(CWmake_immutable()\fR 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 invoke the meta
API.
.PP
Second, you can no longer make changes via the metaclass API, such as
adding attributes. In practice, this won\*(Aqt be a problem, as you rarely
need to do this after first loading the class.
.SH CONCLUSION
.IX Header "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 objects.
.SH AUTHORS
.IX Header "AUTHORS"
.IP \(bu 4
Stevan Little <stevan@cpan.org>
.IP \(bu 4
Dave Rolsky <autarch@urth.org>
.IP \(bu 4
Jesse Luehrs <doy@cpan.org>
.IP \(bu 4
Shawn M Moore <sartak@cpan.org>
.IP \(bu 4
יובל קוג\*(Aqמן (Yuval Kogman) <nothingmuch@woobling.org>
.IP \(bu 4
Karen Etheridge <ether@cpan.org>
.IP \(bu 4
Florian Ragwitz <rafl@debian.org>
.IP \(bu 4
Hans Dieter Pearcey <hdp@cpan.org>
.IP \(bu 4
Chris Prather <chris@prather.org>
.IP \(bu 4
Matt S Trout <mstrout@cpan.org>
.SH "COPYRIGHT AND LICENSE"
.IX Header "COPYRIGHT AND LICENSE"
This software is copyright (c) 2006 by Infinity Interactive, Inc.
.PP
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.