Ruby中的`try`和`& .`（安全导航操作符）有什么区别？ [英] What is the difference between `try` and `&.` (safe navigation operator) in Ruby

问题描述

这是我的代码：

class Order < Grape::Entity
  expose :id { |order, options| order.id.obfuscate }
  expose :time_left_to_review do |order, options|
    byebug
    order&.time_left_to_review # ERROR
  end
  expose :created_at { |order, options| order.last_transition.created_at }
end

# NoMethodError Exception: undefined method `time_left_to_review' for #<Order:0x007f83b9efc970>

我认为&。是一个捷径对于 .try 但我想我错了。有人可能会指出我正确的方向吗？

I thought &. is a shortcut for .try but I guess I was wrong. May someone point me to the right direction regarding what I am missing?

我觉得这不是红宝石相关的。葡萄可能吗？虽然我不知道它是怎么回事。

I feel like it's not ruby related. Grape maybe? Though I don't get how it could be.

推荐答案

&。的工作方式类似于 #try！，而不是 #try 。

&. works like #try!, not #try.

以下是 #try！的描述（来自文档）：

And here is description of #try! (from documentation):

与#try相同，但如果出现NoMethodError异常，则会引发NoMethodError异常接收不是零，并没有实现尝试过的方法。

Same as #try, but will raise a NoMethodError exception if the receiving is not nil and does not implemented the tried method.

所以基本上它可以节省你在<$ c $上调用方法c> nil ，但是如果出现一个对象，它会像往常一样调用它的方法。

So basically it saves you from calling a method on nil, but if an object is presented it will try to call its method as usual.

引用来自Rails文档，并且所以重要的是要强调
，Ruby不提供 #try ，它是Rails，或者更准确地说是ActiveSupport。安全导航操作符&。是Ruby 2.3.0中提供的语言功能。

The quote is from Rails Documentation, and so it's important to emphasize that Ruby does not provide #try, it's Rails, or more accurately ActiveSupport. While safe navigation operator &. is a language feature presented in Ruby 2.3.0.

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