使用&在rails上的ruby阻止sytax: [英] ruby on rails block sytax using &:

问题描述

所以说我有一个Question模型和Answer模型以及Question has_many Answers(这是一个选择题).

So say I have a Question model and an Answer model and Question has_many Answers (it's a multiple choice question).

假设问题是Question对象的集合.

Suppose that questions is a collection of Question objects.

为了收集所有答案，我可以这样做:

In order to collect all the answers I can do this:

questions.collect(&:answers)

两个问题:

1. 此语法的确切含义是什么?是否扩展到

1. What precisely does this syntax mean? Does it expand to

questions.collect { |q| q.answers } 

或者这里还有其他事情吗?

or is there something else going on here?

有没有办法做

questions.collect { |q| q.answers.shuffle } 

使用相同的语法?

collect(&:answers.shuffle) 

没有这样做.

我似乎在Web上的红宝石块的教程中找不到此内容，并且搜索不起作用(搜索引擎会忽略&::").我在一些继承的代码中找到了它.

I can't seem to find this in tutorials on ruby blocks on the web and searching for it doesn't work (search engines ignore "&:"). I found it in some inherited code.

谢谢

推荐答案

是的，第一个问题是N重复的，但是关于第二个问题:否，您不能链接方法. 但是，除了编写可能会让人迷惑的代码之外，没有什么可以阻止您创建自己的工具了:

Yes, the first question is N-duplicated, but regarding the second: no, you cannot chain methods. However, nothing stops you -other than writing code that may puzzle people- to create your own tool:

class Symbol
  def to_proc
    proc do |obj| 
      self.to_s.split(/\./).inject(obj, :send)
    end
  end
end

p ["1", "2", "3"].map(&:"to_i.succ")
# [2, 3, 4]

您甚至可以找到发送参数的方法，尽管它可能不会很漂亮.

You can even find ways to send arguments, though it won't probably be very beautiful.

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