1MooX::HandlesVia(3)   User Contributed Perl Documentation  MooX::HandlesVia(3)
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NAME

6       MooX::HandlesVia - NativeTrait-like behavior for Moo.
7

VERSION

9       version 0.001009
10

SYNOPSIS

12         {
13           package Hashy;
14           use Moo;
15           use MooX::HandlesVia;
16
17           has hash => (
18             is => 'rw',
19             handles_via => 'Hash',
20             handles => {
21               get_val => 'get',
22               set_val => 'set',
23               all_keys => 'keys'
24             }
25           );
26         }
27
28         my $h = Hashy->new(hash => { a => 1, b => 2});
29
30         $h->get_val('b'); # 2
31
32         $h->set_val('a', 'BAR'); # sets a to BAR
33
34         my @keys = $h->all_keys; # returns a, b
35

DESCRIPTION

37       MooX::HandlesVia is an extension of Moo's 'handles' attribute
38       functionality. It provides a means of proxying functionality from an
39       external class to the given atttribute. This is most commonly used as a
40       way to emulate 'Native Trait' behavior that has become commonplace in
41       Moose code, for which there was no Moo alternative.
42

SHORTCOMINGS

44       Due to current Moo implementation details there are some deficiencies
45       in how MooX::HandlesVia in comparison to what you would expect from
46       Moose native traits.
47
48       •   methods delegated via the Moo 'handles' interface are passed the
49           attribue value directly. and there is no way to access the parent
50           class. This means if an attribute is updated any triggers or type
51           coercions WILL NOT fire.
52
53       •   Moo attribute method delegations are passed the attribute value.
54           This is fine for references (objects, arrays, hashrefs..) it means
55           simple scalar types are READ ONLY. This unfortunately means Number,
56           String, Counter, Bool cannot modify the attributes value, rendering
57           them largely useless.
58
59       If these are issues for you, consider Sub::HandlesVia, which uses a
60       different architecture, respecting triggers and coercions, and allowing
61       read-write access to non-reference values. It should be possible to use
62       Sub::HandlesVia as a drop-in replacement for MooX::HandlesVia.
63

PROVIDED INTERFACE/FUNCTIONS

65       process_has(@_)
66           MooX::HandlesVia preprocesses arguments passed to has() attribute
67           declarations via the process_has function. In a given Moo class, If
68           'handles_via' is set to a ClassName string, and 'handles' is set
69           with a hashref mapping of desired moo class methods that should map
70           to ClassName methods, process_has() will create the appropriate
71           binding to create the mapping IF ClassName provides that named
72           method.
73
74             has options => (
75               is => 'rw',
76               handles_via => 'Array',
77               handles => {
78                 mixup => 'shuffle',
79                 unique_options => 'uniq',
80                 all_options => 'elements'
81               }
82             );
83
84       The following handles_via keywords are reserved as shorthand for
85       mapping to Data::Perl:
86
87       •   Hash maps to Data::Perl::Collection::Hash::MooseLike
88
89       •   Array maps to Data::Perl::Collection::Array::MooseLike
90
91       •   String maps to Data::Perl::String::MooseLike
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93       •   Number maps to Data::Perl::Number::MooseLike
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95       •   Bool maps to Data::Perl::Bool::MooseLike
96
97       •   Code maps to Data::Perl::Code
98

SEE ALSO

100       •   Moo
101
102       •   MooX::late
103
104       •   Sub::HandlesVia
105

ORIGINAL AUTHOR

107       Matthew Phillips <mattp@cpan.org>
108

AUTHOR

110       Toby Inkster <tobyink@cpan.org>
111

113       This software is copyright (c) 2020 by Matthew Phillips
114       <mattp@cpan.org>.
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116       This is free software; you can redistribute it and/or modify it under
117       the same terms as the Perl 5 programming language system itself.
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121perl v5.32.1                      2021-01-27               MooX::HandlesVia(3)
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