duelafn has asked for the wisdom of the Perl Monks concerning the following question:

Is it possible to create parameterized Catalyst roles with method attributes? The closest thing a web search finds is this post whose followup message points to a moosex-methodattributes test file which does create a parameterized role, but as far as I can tell doesn't test any attributes. My attempt (below) compiles but does not produce any (chained) actions.

package Serenevy::CatalystX::Role::CRUDForms;
use MooseX::Role::Parameterized -traits => 'MooseX::MethodAttributes::
+Role::Meta::Role';
use namespace::autoclean;
use re 'taint';
use 5.010;

parameter [qw/ name root path_part model_name /] => (
    is       => "rw",
    isa      => "Str",
    required => 1,
);

role {
    my $param = shift;
    my $NAME = $param->name;
    my $ROOT = $param->root;
    my $MODEL = $param->model_name;
    my $PATH_PART = $param->path_part;

    method model => sub { $_[1]->model( $MODEL ) };

    method root => sub :Chained($ROOT) :PathPart($PATH_PART) :CaptureA
+rgs(0) { 1 };

    method list => sub :Chained(root) :PathPart("") :Args(0) {
        my ( $self, $c ) = @_;
        # ...
    };

    # ...
};

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This role is consumed in my controiller via

package RiverbendMath::Controller::Int::FieldClass;
use Moose;
use namespace::autoclean;
use re 'taint';
use 5.010;
BEGIN { extends 'Catalyst::Controller'; }

with 'Serenevy::CatalystX::Role::CRUDForms' => {
    name => "Field Class",
    root => "../int",
    path_part => "field-class",
    model_name => "DB::EntClass",
};

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Catalyst 5.80025; Moose 1.09; MooseX::Role::Parameterized 0.19; MooseX::MethodAttributes 0.24

Good Day,
    Dean

Replies are listed 'Best First'.
Re: Catalyst Parameterized Role with Attributes?
by roman (Monk) on Jan 10, 2012 at 15:03 UTC

    I'm puzzled that nobody commented this topic. Parameterized controller roles seem to me as a handy tool for detailed modeling of parts of action chains.

    I was also confused by the test in MooseX::MethodAttributes distribution because it doesnot work with attributes.

    Unsuccessfull with mixing MooseX::MethodAttributes and MooseX::Role::Parameterized I tried to modify 'action' hash in controller's config (described in Catalyst::Controller) instead. It seems to work. 

    role {
    my $param = shift;
    my $NAME = $param->name;
    my $ROOT = $param->root;
    my $MODEL = $param->model_name;
    my $PATH_PART = $param->path_part;

    method model => sub { $_[1]->model( $MODEL ) };
    method root => sub { ... };
    method list => sub {...};

    # The purpose of this 'before' is to add keys
    # into config hash first (only first) time the config is touched.
    my $config_called;
    before config => sub {
        return if $config_called++;

        my $action_config = shift()->config->{action} ||= {};
        %$action_config = (
            %$action_config,
            root => {
                Chained     => [$ROOT],
                PathPart    => [$PATH_PART],
                CaptureArgs => [0],
            },

            list => {
                Chained  => ['root'],
                PathPart => [''],
                Args     => [0],
            }
        );
    };
};

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