Perl complication failed on “has … => …”

Question

Could anyone help explain the grammer about "has usage ...", "has description ..." in below cgi.pm?

package Mojolicious::Command::cgi;
use Mojo::Base 'Mojolicious::Command';

use Mojo::Server::CGI;
use Mojo::Util 'getopt';

has description => 'Start application with CGI';
has usage => sub { shift->extract_usage };

sub run {
  my ($self, @args) = @_;
  getopt \@args, nph => \(my $nph = 0);
  Mojo::Server::CGI->new(app => $self->app, nph => $nph)->run;
}

1;

Answer 1

See the Mojo::Base documentation . The has function defines an attribute for the class.

In this case Mojo::Command::cgi has a Mojolicious::Command base class and the description attribute defaults to the string supplied, and the usage attribute will be initialized by calling the extract_usage method.