Perl复杂性在"has ... => ...“上失败

Question

谁能帮我解释一下语法“有用法..."，”有描述...“在下面的cgi.pm中？

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

请参阅Mojo::Base documentation。has函数为类定义了一个属性。

在本例中，Mojo::Command::cgi有一个Mojolicious::Command基类，description属性缺省为提供的字符串，usage属性将通过调用extract_usage方法进行初始化。