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 Mite¶

You should be able to use Sub::HandlesVia with Mite 0.001011 or above. Your project will still have a dependency on Sub::HandlesVia.

 package MyApp::Kitchen {
   use MyApp::Mite;
   use Sub::HandlesVia;
   
   has food => (
     is          => 'ro',
     isa         => 'ArrayRef[Str]',
     handles_via => 'Array',
     default     => sub { [] },
     handles     => {
       'add_food'    => 'push',
       'find_food'   => 'grep',
     },
   );
 }
 You should be able to use Sub::HandlesVia with L<Mite> 0.001011 or above.
 Your project will still have a dependency on Sub::HandlesVia.
  package MyApp::Kitchen {
    use MyApp::Mite;
    use Sub::HandlesVia;
    
    has food => (
      is          => 'ro',
      isa         => 'ArrayRef[Str]',
      handles_via => 'Array',
      default     => sub { [] },
      handles     => {
        'add_food'    => 'push',
        'find_food'   => 'grep',
      },
    );
  }

If you have Mite 0.009000 or above, you can probably use its "handles_via" support, and avoid your project having a Sub::HandlesVia dependency!

 package MyApp::Kitchen {
   use MyApp::Mite;
   
   has food => (
     is          => 'ro',
     isa         => 'ArrayRef[Str]',
     handles_via => 'Array',
     default     => sub { [] },
     handles     => {
       'add_food'    => 'push',
       'find_food'   => 'grep',
     },
   );
 }

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_list : SubHV             ..........
         execute_scalar : SubHV             ..........
           execute_void : SubHV             ..........
         execute_method : SubHV         Moose  Mouse  
    execute_method_list : SubHV             ..........
  execute_method_scalar : SubHV             ..........
    execute_method_void : SubHV             ..........
  
  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  
           delete_where : SubHV                       
               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  
                    cmp : SubHV                       
                    div : SubHV  DataP  Moose  Mouse  
                     eq : SubHV                       
                     ge : SubHV                       
                    get : SubHV                       
                     gt : SubHV                       
                     le : SubHV                       
                     lt : SubHV                       
                    mod : SubHV  DataP  Moose  Mouse  
                    mul : SubHV  DataP  Moose  Mouse  
                     ne : SubHV                       
                    set : SubHV         Moose         
                    sub : SubHV  DataP  Moose  Mouse  
  
  Scalar =============================================
            make_getter : SubHV                       
            make_setter : SubHV                       
       scalar_reference : SubHV                       
  
  String =============================================
                 append : SubHV  DataP  Moose  Mouse  
                  chomp : SubHV  DataP  Moose  Mouse  
                   chop : SubHV  DataP  Moose  Mouse  
                  clear : SubHV  DataP  Moose  Mouse  
                    cmp : SubHV                       
                   cmpi : SubHV                       
               contains : SubHV                       
             contains_i : SubHV                       
              ends_with : SubHV                       
            ends_with_i : SubHV                       
                     eq : SubHV                       
                    eqi : SubHV                       
                     fc : SubHV                       
                     ge : SubHV                       
                    gei : SubHV                       
                    get : SubHV                       
                     gt : SubHV                       
                    gti : SubHV                       
                    inc : SubHV  DataP  Moose  Mouse  
                     lc : SubHV                       
                     le : SubHV                       
                    lei : SubHV                       
                 length : SubHV  DataP  Moose  Mouse  
                     lt : SubHV                       
                    lti : SubHV                       
                  match : SubHV  DataP  Moose  Mouse  
                match_i : SubHV                       
                     ne : SubHV                       
                    nei : SubHV                       
                prepend : SubHV  DataP  Moose  Mouse  
                replace : SubHV  DataP  Moose  Mouse  
       replace_globally : SubHV                Mouse  
                  reset : SubHV                       
                    set : SubHV                       
            starts_with : SubHV                       
          starts_with_i : SubHV                       
                 substr : SubHV  DataP  Moose  Mouse  
                     uc : SubHV

For further details see: Array, Bool, Code, Counter, Hash, Number, Scalar, and String.

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',
    }