如何取消评估所需的Ruby文件? [英] How to cancel evaluating a required Ruby file?

问题描述

file1需要file2，并且我希望能够在特定条件下取消对file2的评估而不会退出整个过程.

file1 requires file2, and I want to be able to cancel evaluating file2 under certain conditions without exiting the whole process.

# file1.rb
  puts "In file 1"
  require 'file2'
  puts "Back in file 1"

# file2.rb
  puts "In file 2"
  # return if some_conditional
  puts "Still in file 2"

运行file1时，我想看到的输出是:

When running file1, the output I want to see is:

In file 1
In file 2
Back in file 1

目标是从不打印Still in file 2，而打印Back in file 1. 在file2中我可以做些什么吗?

The goal is for Still in file 2 to never print, while Back in file 1 does print. Is there anything I can do in file2 to make this possible?

在这里我不能使用exit/exit!/abort，因为Back in file 1将永远不会打印.我可以使用raise/fail，但是要做到这一点，我必须更改file1和rescue失败的require.我希望找到一种不涉及更改file1的方法.

I can't use exit/exit!/abort here because Back in file 1 will never print. I could use raise/fail, but to do that I would have to change file1 and rescue the failed require. I'm hoping to find a way that doesn't involve altering file1.

更新:

已添加顶级退货"功能 .

A "top-level return" feature has been added.

推荐答案

更新:

已添加顶级退货"功能 .

A "top-level return" feature has been added.

原始:

评论员 matt 指出功能4840可以完全满足我的要求自2011年6月以来一直在讨论.此外，该功能还一直在核心团队中进行讨论，直到2015年11月有关Ruby新功能的会议.

Commenter matt pointed out that Feature 4840, which would do exactly what I'm asking about, has been in discussion since June 2011. Further, the feature was still being discussed as late as November 2015 in core team meetings regarding new Ruby features.

设计这样的功能会涉及很多困难；有关优缺点的清单，我强烈建议您查看讨论内容.

There are a lot of difficulties involved in designing a feature like this; for a list of the pros and cons, I highly suggest checking out the discussions.

建议的功能将允许在使用以下任何顶级语句时退出所需的文件:

The proposed feature would allow exiting the required file while using any of the the following top-level statements:

if condition
  return
end

while condition
  # ...
  return
end

begin
  # ...
  return
rescue
  # ...
  return
ensure
  # ...
  return
end

并且它不会在以下语句中退出所需的文件:

And it would not exit the required file in the following statements:

class Foo
  return # LocalJumpError
end

def foo
  return # returns from method, not from required file
end

proc do
  return # LocalJumpError
end

x = -> { return } # returns as from lambda, not from required file

由于该功能仍未实现，我将赏金授予 steenslag ，以成功解决该问题(如最初所写)而不是精神.

Since the feature remains unimplemented, I have awarded the bounty to steenslag for successfully solving the problem (as originally written) to the letter, if not the spirit.

这篇关于如何取消评估所需的Ruby文件?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！