MooX::HandlesVia - NativeTrait-like behavior for Moo.
version 0.001008
{
package Hashy;
use Moo;
use MooX::HandlesVia;
has hash => (
is => 'rw',
handles_via => 'Hash',
handles => {
get_val => 'get',
set_val => 'set',
all_keys => 'keys'
}
);
}
my $h = Hashy->new(hash => { a => 1, b => 2});
$h->get_val('b'); # 2
$h->set_val('a', 'BAR'); # sets a to BAR
my @keys = $h->all_keys; # returns a, b
MooX::HandlesVia is an extension of Moo's 'handles' attribute functionality. It provides a means of proxying functionality from an external class to the given atttribute. This is most commonly used as a way to emulate 'Native Trait' behavior that has become commonplace in Moose code, for which there was no Moo alternative.
Due to current Moo implementation details there are some deficiencies in how MooX::HandlesVia in comparison to what you would expect from Moose native traits.
- methods delegated via the Moo 'handles' interface are passed the attribue value directly. and there is no way to access the parent class. This means if an attribute is updated any triggers or type coercions WILL NOT fire.
- Moo attribute method delegations are passed the attribute value. This is fine for references (objects, arrays, hashrefs..) it means simple scalar types are READ ONLY. This unfortunately means Number, String, Counter, Bool cannot modify the attributes value, rendering them largely useless.
-
process_has(@_)
MooX::HandlesVia preprocesses arguments passed to has() attribute declarations via the process_has function. In a given Moo class, If 'handles_via' is set to a ClassName string, and 'handles' is set with a hashref mapping of desired moo class methods that should map to ClassName methods, process_has() will create the appropriate binding to create the mapping IF ClassName provides that named method.
has options => ( is => 'rw', handles_via => 'Array', handles => { mixup => 'shuffle', unique_options => 'uniq', all_options => 'elements' } );
The following handles_via keywords are reserved as shorthand for mapping to Data::Perl:
- Hash maps to Data::Perl::Collection::Hash::MooseLike
- Array maps to Data::Perl::Collection::Array::MooseLike
- String maps to Data::Perl::String::MooseLike
- Number maps to Data::Perl::Number::MooseLike
- Bool maps to Data::Perl::Bool::MooseLike
- Code maps to Data::Perl::Code
Matthew Phillips mattp@cpan.org
This software is copyright (c) 2015 by Matthew Phillips mattp@cpan.org.
This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.