use Perl

• Ohh, Moose Golf! (Score:1)

  by Stevan (6065) <reversethis-{moc ... {elttil.navets}> on 2009.02.20 13:36 (#67510) Journal

  So, in the interest of TIMTOWTDI, here is another approach that uses coercion to extract the params list from the controller object.

  package PIPs::QueryParams;
  use Moose;
  use Moose::Util::TypeContraints;
  use PIPs::QueryParams::Param;
  
  # I am assuming this is the name
  # of your controller class and
  # it is a non-Moose class, if it is
  # a Moose class, you can remove this
  # (assuming the class is already loaded)
  # because Moose does this for you
  class_type 'PIPs::Controller';
  
  subtype 'PIPs::ListOfParams'
      => as 'ArrayRef[PIPs::QueryParams::Param]';
  
  coerce 'PIPs::ListOfParams'
      => from 'PIPs::Controller'
      => via {
          my $controller = $_;
          my @params;
          my $allowed_query_params = $controller->allowed_query_params;
          foreach my $name ( sort keys  %$allowed_query_params) {
              my $args = $allowed_query_params->{$name};
              $args->{name} = $name;
              push @params => PIPs::QueryParams::Param->new(%$args);
          }
          return \@params;
      };
  
  has params => (
      is     => 'ro',
      isa    => 'PIPs::ListOfParams',
      coerce => 1,
  );
  
  __PACKAGE__->meta->make_immutable;
  
  no Moose; 1;

  And then your code would look like this ...

  my $params = PIPs::QueryParams->new( params => $controller );
  my $list   = $params->params;
  say $_->name foreach @$list;

  Now, passing a controller where your supposed to pass params does seem a little odd, so perhaps this isnt the best example. However you could just as easily pass in the $controller->allowed_query_params and do the coercion on the HashRef[HashRef] type (or better yet, use MooseX::Types::Structured to define a stricter Dictionary type).

  One of the benefits I see with using types and coercion is that since types are global, this promotes cross cutting re-use since now any class that needs a list of PIPs::QueryParams::Param objects and happens to have easy access to a $controller object can use this coercion.

  Anyway, glad your enjoying the Moose :)

  - Stevan

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