MooseX::SetOnce − write−once, read−many attributes for Moose
Add the "SetOnce" trait to attributes:
package Class; use Moose; use MooseX::SetOnce; has some_attr => ( is => 'rw', traits => [ qw(SetOnce) ], );
...and then you can only set them once:
my $object = Class−>new; $object−>some_attr(10); # works fine $object−>some_attr(20); # throws an exception: it's already set!
The ’SetOnce’ attribute lets your class have attributes that are not lazy and not set, but that cannot be altered once set.
The logic is very simple: if you try to alter the value of an attribute with the SetOnce trait, either by accessor or writer, and the attribute has a value, it will throw an exception.
If the attribute has a clearer, you may clear the attribute and set it again.
Ricardo SIGNES <rjbs AT cpan DOT org>
This software is copyright (c) 2011 by Ricardo SIGNES .
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.