=head1 NAME MooseX::Failover - Instantiate Moose classes with failover =head1 VERSION v0.1.3 =head1 SYNOPSIS # In your class: package MyClass; use Moose; with 'MooseX::Failover'; # When using the class my $obj = MyClass->new( %args, failover_to => 'OtherClass' ); # If %args contains missing or invalid values or new otherwise # fails, then $obj will be of type "OtherClass". =head1 INSTALLATION See L. =head2 Required Modules This distribution requires Perl v5.10.0. This distribution requires the following modules: =over 4 =item * L (version 0.20) =item * L (version 2.1101) =item * L =back This distribution recommends the following modules: =over 4 =item * L =back =head1 RECENT CHANGES =head2 Enhancements =over 4 =item * PerlX::Maybe is no longer needed. =back See the F file for a longer revision history. =head1 DESCRIPTION This role provides constructor failover for L classes. If a class cannot be instantiated because of invalid arguments (perhaps from an untrusted source), then instead it returns the failover class (passing the same arguments to that class). This allows for cleaner design, by not forcing you to duplicate type checking for class parameters. Note that this is roughly equivalent to using my $obj = eval { MyClass->new(%args) // OtherClass->new( %args, error => $@ ); Note that your failover class should support the same methods as the original class. A use case for this role would be for instantiating L objects, where the failover is a Web::Machine::Resource object that returns an error page. Ideally, your failover class would satisy the Liskov Substitution Principle, so that (roughly) all provable properties of the original class are also provable of the failover class. In practice, we only care about the properties (methods and attributes) that are actually used in our programs. =head1 AUTHOR Robert Rothenberg C<> =head1 Acknowledgements =over =item Thermeon Europe. =item Piers Cawley. =back =head1 COPYRIGHT Copyright 2014 Thermeon Europe. This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself. This program is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose.