在 Moose 构建器中使用子引用

Question

Moose 文档提到 builder 属性 for attribute in class definiton 应该是一个字符串，其中包含将被调用以构建相关属性的函数的名称。然而，简单的测试表明子引用也可以工作：

has 'some_attribute' => (
    is => 'ro',
    lazy => 1,
    builder => sub {
        require SomeModule::Heavy;
        return SomeModule::Heavy->new($_[0]);
    },
);

我是否遗漏了文档中的内容？ builder 是否正式支持子引用的使用？

Answer 1

Moose manual 说：

You can also provide a subroutine reference for default. This reference will be called as a method on the object. […] As an alternative to using a subroutine reference, you can supply a builder method for your attribute. This has several advantages. First, it moves a chunk of code to its own named method, which improves readability and code organization. Second, because this is a named method, it can be subclassed or provided by a role.

因此，如果您对 builder 使用子例程引用，那么您将失去这些优势。我认为子例程引用是副作用，没有实际应用。

在 Moose 构建器中使用子引用

Using sub reference with Moose builder

perl

moose