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|
=pod
=encoding utf-8
=head1 NAME
Sub::HandlesVia::Manual::WithGeneric - using Sub::HandlesVia with generic Perl classes
=head1 MANUAL
Sub::HandlesVia allows you to delegate methods from your class to the
values of your objects' attributes.
Conceptually, it allows you to define C<< $object->push_number($n) >>
to be a shortcut for C<< $object->numbers->push($n) >> except that
C<< $object->numbers >> is an arrayref, so doesn't have methods you
can call on it like C<push>.
For Moose and Mouse, Sub::HandlesVia can use their metaobject protocols
to grab an attribute's definition and install the methods it needs to.
For Moo, it can wrap C<has> and do its stuff that way. For other classes,
you need to be more explicit and tell it what methods to delegate to
what attributes.
package Kitchen {
# constructor
sub new {
my ( $class, %arg ) = @_;
$arg{food} ||= [];
return bless( \%arg, $class );
}
# getter/setter for `food`
sub food {
(@_ == 1) ? $_[0]{food} : ( $_[0]{food} = $_[1] );
}
use Sub::HandlesVia qw( delegations );
delegations(
attribute => 'food'
handles_via => 'Array',
handles => {
'add_food' => 'push',
'find_food' => 'grep',
},
);
}
Setting C<attribute> to "food" means that when Sub::HandlesVia needs
to get the food list, it will call C<< $kitchen->food >> and when
it needs to set the food list, it will call C<< $kitchen->food($value) >>.
If you have separate getter and setter methods, just do:
attribute => [ 'get_food', 'set_food' ],
Or if you don't have any accessors and want Sub::HandlesVia to
directly access the underlying hashref:
attribute => '{food}',
Or maybe you have a setter, but want to use hashref access for the
getter:
attribute => [ '{food}', 'set_food' ],
Or maybe you still want direct access for the getter, but your
object is a blessed arrayref instead of a blessed hashref:
attribute => [ '[7]', 'set_food' ],
Or maybe your needs are crazy unique:
attribute => [ \&getter, \&setter ],
The coderefs are passed the instance as their first argument, and
the setter is also passed a value to set.
Really, I don't think there's any object system that this won't work
for!
If you supply an arrayref with a getter and setter, it's also
possible to supply a third argument which is a coderef or string
which will be called as a method if needing to "reset" the value.
This can be thought of like a default or builder.
(The C<delegations> function can be imported into Moo/Mouse/Moose classes
too, in which case the C<attribute> needs to be the same attribute name
you passed to C<has>. You cannot use a arrayref, coderef, hash key, or
array index.)
=head1 BUGS
Please report any bugs to
L<https://github.com/tobyink/p5-sub-handlesvia/issues>.
=head1 SEE ALSO
Misc advanced documentation:
L<Sub::HandlesVia::Manual::Advanced>.
L<Sub::HandlesVia>.
Documentation for delegatable methods:
L<Sub::HandlesVia::HandlerLibrary::Array>,
L<Sub::HandlesVia::HandlerLibrary::Blessed>,
L<Sub::HandlesVia::HandlerLibrary::Bool>,
L<Sub::HandlesVia::HandlerLibrary::Code>,
L<Sub::HandlesVia::HandlerLibrary::Counter>,
L<Sub::HandlesVia::HandlerLibrary::Enum>,
L<Sub::HandlesVia::HandlerLibrary::Hash>,
L<Sub::HandlesVia::HandlerLibrary::Number>,
L<Sub::HandlesVia::HandlerLibrary::Scalar>, and
L<Sub::HandlesVia::HandlerLibrary::String>.
=head1 AUTHOR
Toby Inkster E<lt>tobyink@cpan.orgE<gt>.
=head1 COPYRIGHT AND LICENCE
This software is copyright (c) 2022 by Toby Inkster.
This is free software; you can redistribute it and/or modify it under
the same terms as the Perl 5 programming language system itself.
=head1 DISCLAIMER OF WARRANTIES
THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
|
