访问 Struct.new 块中的类变量

发布于 2024-10-15 16:59:47 字数 815 浏览 2 评论 0原文

我正在使用 Struct.new 动态创建新类（我们正在使用一些实体建模中间件，我想动态生成具体类型以进行序列化）。

本质上我有这段代码：

module A
    def self.init_on(target)
        target.foo = 123
    end
end

$base_module = A


module Test
    C = Struct.new(:id) do
        include $base_module

        @@base = $base_module

        def initialize
            @@base.init_on(self)
        end

        attr_accessor :foo
    end
end

c = Test::C.new
puts c.foo

当我运行测试时出现此错误：

test2.rb:17:in initialize': uninitialized class variable @@base in Test::C (NameError) 来自 test2.rb:24:innew' from test2.rb:24:in `'

根据我对 Struct.new 的理解，该块是在正在创建的类的上下文中执行的，因此 @@base 应该是可解析的。

感谢您抽出时间！

编辑：谢谢 - 我做了 init_on self.init_on 并使用了 class_variable_set 而不是 instance_variable_set。现在可以了！

原文

I'm using Struct.new to create new classes on the fly (we're using some entity modelling middleware, and I want to generate concrete types on the fly for serialization).

In essence I have this code:

module A
    def self.init_on(target)
        target.foo = 123
    end
end

$base_module = A


module Test
    C = Struct.new(:id) do
        include $base_module

        @@base = $base_module

        def initialize
            @@base.init_on(self)
        end

        attr_accessor :foo
    end
end

c = Test::C.new
puts c.foo

I get this error when I run my test:

test2.rb:17:in initialize': uninitialized class variable @@base in Test::C (NameError) from test2.rb:24:innew'
from test2.rb:24:in `'

From my understanding of Struct.new, the block is executed with the context of the class being created, so @@base should be resolvable.

Thanks for your time!

Edit:
Thanks - I made init_on self.init_on and used class_variable_set rather than instance_variable_set. It now works!

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