NAME Sub::HandlesVia - alternative handles_via implementation SYNOPSIS package Kitchen { use Moo; use Sub::HandlesVia; use Types::Standard qw( ArrayRef Str ); has food => ( is => 'ro', isa => ArrayRef[Str], handles_via => 'Array', default => sub { [] }, handles => { 'add_food' => 'push', 'find_food' => 'grep', }, ); } my $kitchen = Kitchen->new; $kitchen->add_food('Bacon'); $kitchen->add_food('Eggs'); $kitchen->add_food('Sausages'); $kitchen->add_food('Beans'); my @foods = $kitchen->find_food(sub { /^B/i }); DESCRIPTION If you've used Moose's native attribute traits, or MooX::HandlesVia before, you should have a fairly good idea what this does. Why re-invent the wheel? Well, this is an implementation that should work okay with Moo, Moose, Mouse, and any other OO toolkit you throw at it. One ring to rule them all, so to speak. Also, unlike MooX::HandlesVia, it honours type constraints, plus it doesn't have the limitation that it can't mutate non-reference values. Using with Moo You should be able to use it as a drop-in replacement for MooX::HandlesVia. package Kitchen { use Moo; use Sub::HandlesVia; use Types::Standard qw( ArrayRef Str ); has food => ( is => 'ro', isa => ArrayRef[Str], handles_via => 'Array', default => sub { [] }, handles => { 'add_food' => 'push', 'find_food' => 'grep', }, ); } Using with Mouse It works the same as Moo basically. package Kitchen { use Mouse; use Sub::HandlesVia; use Types::Standard qw( ArrayRef Str ); has food => ( is => 'ro', isa => ArrayRef[Str], handles_via => 'Array', default => sub { [] }, handles => { 'add_food' => 'push', 'find_food' => 'grep', }, ); } You are not forced to use Types::Standard. Mouse native types should work fine. package Kitchen { use Mouse; use Sub::HandlesVia; has food => ( is => 'ro', isa => 'ArrayRef[Str]', handles_via => 'Array', default => sub { [] }, handles => { 'add_food' => 'push', 'find_food' => 'grep', }, ); } Sub::HandlesVia will also recognize MooseX::NativeTraits-style traits. It will jump in and handle them before MooseX::NativeTraits notices! package Kitchen { use Mouse; use Sub::HandlesVia; has food => ( is => 'ro', isa => 'ArrayRef[Str]', traits => ['Array'], default => sub { [] }, handles => { 'add_food' => 'push', 'find_food' => 'grep', }, ); } (If you have a mouse in your kitchen though, that might not be very hygienic.) Using with Moose It works the same as Mouse basically. package Kitchen { use Moose; use Sub::HandlesVia; use Types::Standard qw( ArrayRef Str ); has food => ( is => 'ro', isa => ArrayRef[Str], handles_via => 'Array', default => sub { [] }, handles => { 'add_food' => 'push', 'find_food' => 'grep', }, ); } You are not forced to use Types::Standard. Moose native types should work fine. package Kitchen { use Moose; use Sub::HandlesVia; has food => ( is => 'ro', isa => 'ArrayRef[Str]', handles_via => 'Array', default => sub { [] }, handles => { 'add_food' => 'push', 'find_food' => 'grep', }, ); } Sub::HandlesVia will also recognize native-traits-style traits. It will jump in and handle them before Moose notices! package Kitchen { use Moose; use Sub::HandlesVia; has food => ( is => 'ro', isa => 'ArrayRef[Str]', traits => ['Array'], default => sub { [] }, handles => { 'add_food' => 'push', 'find_food' => 'grep', }, ); } (If you have a moose in your kitchen, that might be even worse than the mouse.) Using with Anything 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 `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 { use Class::Tiny { food => sub { [] }, }; use Sub::HandlesVia qw( delegations ); delegations( attribute => 'food' handles_via => 'Array', handles => { 'add_food' => 'push', 'find_food' => 'grep', }, ); } Setting `attribute` to "food" means that when Sub::HandlesVia needs to get the food list, it will call `$kitchen->food` and when it needs to set the food list, it will call `$kitchen->food($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 `delegations` function can be imported into Moo/Mouse/Moose classes too, in which case the `attribute` needs to be the same attribute name you passed to `has`. You cannot use a arrayref, coderef, hash key, or array index.) What methods can be delegated to? The following table compares Sub::HandlesVia with Data::Perl, Moose native traits, and MouseX::NativeTraits. Array =========================================== accessor : SubHV DataP Moose Mouse all : SubHV DataP all_true : SubHV any : SubHV Mouse apply : SubHV Mouse clear : SubHV DataP Moose Mouse count : SubHV DataP Moose Mouse delete : SubHV DataP Moose Mouse elements : SubHV DataP Moose Mouse fetch : Mouse (alias: get) first : SubHV DataP Moose Mouse first_index : SubHV DataP Moose flatten : SubHV DataP flatten_deep : SubHV DataP for_each : SubHV Mouse for_each_pair : SubHV Mouse get : SubHV DataP Moose Mouse grep : SubHV DataP Moose Mouse head : SubHV DataP insert : SubHV DataP Moose Mouse is_empty : SubHV DataP Moose Mouse join : SubHV DataP Moose Mouse map : SubHV DataP Moose Mouse max : SubHV maxstr : SubHV min : SubHV minstr : SubHV natatime : SubHV DataP Moose not_all_true : SubHV pairfirst : SubHV pairgrep : SubHV pairkeys : SubHV pairmap : SubHV pairs : SubHV pairvalues : SubHV pick_random : SubHV pop : SubHV DataP Moose Mouse print : SubHV DataP product : SubHV push : SubHV DataP Moose Mouse reduce : SubHV DataP Moose Mouse reductions : SubHV remove : Mouse (alias: delete) reset : SubHV reverse : SubHV DataP sample : SubHV set : SubHV DataP Moose Mouse shallow_clone : SubHV DataP Moose shift : SubHV DataP Moose Mouse shuffle : SubHV DataP Moose Mouse shuffle_in_place : SubHV sort : SubHV DataP Moose Mouse sort_by : Mouse (sort) sort_in_place : SubHV DataP Moose Mouse sort_in_place_by : Mouse (sort_in_place) splice : SubHV DataP Moose Mouse store : Mouse (alias: set) sum : SubHV tail : SubHV DataP uniq : SubHV DataP Moose Mouse uniq_in_place : SubHV uniqnum : SubHV uniqnum_in_place : SubHV uniqstr : SubHV uniqstr_in_place : SubHV unshift : SubHV DataP Moose Mouse Bool ============================================ not : SubHV DataP Moose Mouse reset : SubHV set : SubHV DataP Moose Mouse toggle : SubHV DataP Moose Mouse unset : SubHV DataP Moose Mouse Code ============================================ execute : SubHV DataP Moose Mouse execute_method : SubHV Moose Mouse Counter ========================================= dec : SubHV DataP Moose Mouse inc : SubHV DataP Moose Mouse reset : SubHV DataP Moose Mouse set : SubHV Moose Mouse Hash ============================================ accessor : SubHV DataP Moose Mouse all : SubHV DataP clear : SubHV DataP Moose Mouse count : SubHV DataP Moose Mouse defined : SubHV DataP Moose Mouse delete : SubHV DataP Moose Mouse elements : SubHV DataP Moose Mouse exists : SubHV DataP Moose Mouse fetch : Mouse (alias: get) for_each_key : SubHV Mouse for_each_pair : SubHV Mouse for_each_value : SubHV Mouse get : SubHV DataP Moose Mouse is_empty : SubHV DataP Moose Mouse keys : SubHV DataP Moose Mouse kv : SubHV DataP Moose Mouse reset : SubHV set : SubHV DataP Moose Mouse shallow_clone : SubHV DataP Moose sorted_keys : SubHV Mouse store : Mouse (alias: set) values : SubHV DataP Moose Mouse Number ========================================== abs : SubHV DataP Moose Mouse add : SubHV DataP Moose Mouse div : SubHV DataP Moose Mouse get : SubHV mod : SubHV DataP Moose Mouse mul : SubHV DataP Moose Mouse set : SubHV Moose sub : SubHV DataP Moose Mouse String ========================================== append : SubHV DataP Moose Mouse chomp : SubHV DataP Moose Mouse chop : SubHV DataP Moose Mouse clear : SubHV DataP Moose Mouse get : SubHV inc : SubHV DataP Moose Mouse length : SubHV DataP Moose Mouse match : SubHV DataP Moose Mouse prepend : SubHV DataP Moose Mouse replace : SubHV DataP Moose Mouse replace_globally : SubHV Mouse reset : SubHV set : SubHV substr : SubHV DataP Moose Mouse Method Chaining Say you have the following handles_via => 'Array', handles => { 'add_food' => 'push', 'find_food' => 'grep', 'remove_food' => 'pop', }, Now `$kitchen->remove_food` will remove the last food on the list and return it. But what if we don't care about what food was removed? We just want to remove the food and discard it. You can do this: handles_via => 'Array', handles => { 'add_food' => 'push', 'find_food' => 'grep', 'remove_food' => 'pop...', }, Now the `remove_food` method will return the kitchen object instead of returning the food. This makes it suitable for chaining method calls: # remove the three most recent foods $kitchen->remove_food->remove_food->remove_food; Hand Waving Sub::HandlesVia tries to be strict by default, but you can tell it to be less rigourous checking method arguments, etc using the `~` prefix: handles_via => 'Array', handles => { 'find_food' => '~grep', }, CodeRefs You can delegate to coderefs: handles_via => 'Array', handles => { 'find_healthiest' => sub { my $foods = shift; ... }, } Named Methods Let's say "FoodList" is a class where instances are blessed arrayrefs of strings. isa => InstanceOf['FoodList'], handles_via => 'Array', handles => { 'find_food' => 'grep', 'find_healthiest_food' => 'find_healthiest', }, Now `$kitchen->find_food($coderef)` does this (which breaks encapsulation of course): my @result = grep $coderef->(), @{ $kitchen->food }; And `$kitchen->find_healthiest_food` does this: $kitchen->food->find_healthiest Basically, because `find_healthiest` isn't one of the methods offered by Sub::HandlesVia::HandlerList::Array, it assumes you want to call it on the arrayref like a proper method. Currying Favour All this talk of food is making me hungry, but as much as I'd like to eat a curry right now, that's not the kind of currying we're talking about. handles_via => 'Array', handles => { 'get_food' => 'get', }, `$kitchen->get_food(0)` will return the first item on the list. `$kitchen->get_food(1)` will return the second item on the list. And so on. handles_via => 'Array', handles => { 'first_food' => [ 'get' => 0 ], 'second_food' => [ 'get' => 1 ], }, I think you already know what this does. Right? And yes, currying works with coderefs. handles_via => 'Array', handles => { 'blargy' => [ sub { ... }, @curried ], }, Pick and Mix isa => ArrayRef|HashRef, handles_via => [ 'Array', 'Hash' ], handles => { the_keys => 'keys', ship_shape => 'sort_in_place', } Here you have an attribute which might be an arrayref or a hashref. When it's an arrayref, `$object->ship_shape` will work nicely, but `$object->the_keys` will fail badly. Still, this sort of thing can kind of make sense if you have an object that overloads both `@{}` and `%{}`. Sometime a method will be ambiguous. For example, there's a `get` method for both hashes and arrays. In this case, the array one will win because you listed it first in `handles_via`. But you can be specific: isa => ArrayRef|HashRef, handles_via => [ 'Array', 'Hash' ], handles => { get_foo => 'Array->get', get_bar => 'Hash->get', } BUGS Please report any bugs to . (There are known bugs for Moose native types that do coercion.) SEE ALSO Moose, MouseX::NativeTraits, Data::Perl, MooX::HandlesVia. AUTHOR Toby Inkster . COPYRIGHT AND LICENCE This software is copyright (c) 2020 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. 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.