The Perl Toolchain Summit needs more sponsors. If your company depends on Perl, please support this very important event.
LNATION / MooX-VariantAttribute-0.09 / README.md

NAME

MooX::VariantAttribute - a щ（ﾟДﾟщ）Attribute...

VERSION

Version 0.04

SYNOPSIS

package Backwards::World;
use Moo;
use MooX::VariantAttribute;
use Type::Standards qw/Object Str/;

variant parser => (
    given => Object,
    when => [
        'Test::Parser::One' => {
            alias => {
                parse_string => 'parse',
                # parse_file exists 
            },
        },
        'Random::Parser::Two' => {
            alias => {
                # parse_string exists
                parse_file   => 'parse_from_file', 
            },
        },
        'Another::Parser::Three' => {
            alias => { 
                parse_string => 'meth_one',
                parse_file   => 'meth_two', 
            },
        },
    ],
);

variant string => (
    given => Str,
    when => [
        'one' => { 
            run => sub { return "$_[2] - cold, cold, cold inside" },
        },
        'two' => {
            run => sub { return "$_[2] - don't look at me that way"; },
        },
        'three' => {
            run => sub { return "$_[2] - how hard will i fall if I live a double life"; },
        },
    ],
);

variant refs => (
    given => sub { ref $_[1] or ref \$_[1] }, 
    when => [
        'SCALAR' => { 
            run => sub { 
                return sprintf "refs returned - %s - %s", $_[1], $_[2]; 
            },
        },
        'HASH' => {
            run => sub { 
                return sprintf "refs returned - %s - %s", 
                    $_[1], (join(',', map { sprintf '%s=>%s', $_, $_[2]->{$_} } keys %{ $_[2] })); 
            },
        },
        'ARRAY' => {
            run => sub { 
                return sprintf "refs returned - %s - %s", $_[1], join(',', @{ $_[2] }) 
            },
        },
    ],
);

Description

"I'm just a attribute with a trigger", when you...

use MooX::VariantAttribute;

Magically a role is added..

with 'MooX::VariantAttribute::Role';

MooX::VariantAttribute::Role is a Moo::Role that contains the variant attributes *trigger* logic.

variant

Multiple variant attributes can be declared, they are read in as a list. Each will be transformed into a Moo Attribute with a trigger. 

variant 'one' => (
    given => Str,
    when => [
        one => { run => sub { return 'one' } },
    ],
);

.....

has one => (
    is => 'rw',
    trigger => sub {
        return $_[0]->_given_when($_[1], $spec{given}, $spec{when}, $name);
    }
);

Variants should always have two key/value pairs, given and when, given accepts a code reference or Type::Tiny object. When the code reference is called two parameters are passed the first $self the second the $new value. Type::Tiny objects are called with the $new value.

given => sub { my $self = shift; ref $_[1] },

When is well when it gets more complicated. *when* should always be an array reference of pairs. The first value is the *matching* value it can be a SCALAR, ARRAY, HASH maybe even a Object. The second value has to be a hash reference with two optional keys run and alias. run should always be a code reference it will be passed $self, the $value returned from given, and the $new value. 

package Backwards::World;
use Moo;
use MooX::VariantAttribute;
use Types::Standard qw/Any/;

variant hello => (
    given => Any,
    when => [
        { one => 'two' } => {
            run => sub { return keys %{ $_[2] } },
        },
        { three => 'four' } => {
            run => sub { return values %{ $_[2] } },
        },
        [ qw/five six/ ] => {
            run => sub { return $_[2]->[1] },
        },
        seven => {
            run => sub { return $_[0]->hello({ one => 'two' }) },
        }
    ],
);

$object = Backwards::World->new( hello => 'one' );

$object->hello # one;

$object->hello({ three => 'four' }); # four;
$object->hello, # four;

$object->hello([ qw/five six/ ]), # six;
$object->hello, # six;

$object->hello('seven'), # one;
$object->hello, # one;

AUTHOR

Robert Acock, <thisusedtobeanemail at gmail.com>

BUGS

Please report any bugs or feature requests to bug-moox-variantattribute at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=MooX-VariantAttribute. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.

SUPPORT

You can find documentation for this module with the perldoc command.

perldoc MooX::VariantAttribute

You can also look for information at:

ACKNOWLEDGEMENTS

LICENSE AND COPYRIGHT

Copyright 2017 Robert Acock.

This program is free software; you can redistribute it and/or modify it under the terms of the the Artistic License (2.0). You may obtain a copy of the full license at:

http://www.perlfoundation.org/artistic_license_2_0

Any use, modification, and distribution of the Standard or Modified Versions is governed by this Artistic License. By using, modifying or distributing the Package, you accept this license. Do not use, modify, or distribute the Package, if you do not accept this license.

If your Modified Version has been derived from a Modified Version made by someone other than you, you are nevertheless required to ensure that your Modified Version complies with the requirements of this license.

This license does not grant you the right to use any trademark, service mark, tradename, or logo of the Copyright Holder.

This license includes the non-exclusive, worldwide, free-of-charge patent license to make, have made, use, offer to sell, sell, import and otherwise transfer the Package with respect to any patent claims licensable by the Copyright Holder that are necessarily infringed by the Package. If you institute patent litigation (including a cross-claim or counterclaim) against any party alleging that the Package constitutes direct or contributory patent infringement, then this Artistic License to you shall terminate on the date that such litigation is filed.

Disclaimer of Warranty: THE PACKAGE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS "AS IS' AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES. THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT ARE DISCLAIMED TO THE EXTENT PERMITTED BY YOUR LOCAL LAW. UNLESS REQUIRED BY LAW, NO COPYRIGHT HOLDER OR CONTRIBUTOR WILL BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING IN ANY WAY OUT OF THE USE OF THE PACKAGE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

POD ERRORS

Hey! The above document had some coding errors, which are explained below: