Moose只读属性特征以及如何设置它们？

Question

如何设置Moose只读属性特征？

package AttrTrait;
use Moose::Role;
has 'ext' => ( isa => 'Str', is => 'ro' );

package Class;
has 'foo' => ( isa => 'Str', is => 'ro', traits => [qw/AttrTrait/] );

package main;
my $c = Class->new( foo => 'ok' );
$c->meta->get_attribute('foo')->ext('die') # ro attr trait

如果您不能在构造函数或运行时设置它,那么Read Only属性特征的目的是什么？在Moose :: Meta :: Attribute中有什么我想念的吗？有没有办法设置它meta？

$c->meta->get_attr('ext')->set_value('foo') # doesn't work either (attribute trait provided not class provided method)

Answer 1

您可以在构造函数中设置它:

package Class;
has 'foo' => ( isa => 'Str', is => 'ro', ext => 'whatever', traits => ['AttrTrait'] );

您只需将它传递给正确的构造函数(属性的构造函数).