CoffeeScript... 中是否省略了“do...while”循环？

发布于 2024-11-08 15:37:05 字数 345 浏览 0 评论 0原文

在 CoffeeScript 中，while 循环是标准的：

while x()
   y()

但是，以下¹ 不起作用：

do
  y()
while x()

这只是第一个示例的糖衣：

y() while x()

CoffeeScript 是否带有内置的in 循环至少执行一次？

¹顺便说一句，do 是一个关键字 - 它用于调用匿名函数。

原文

In CoffeeScript, the while loop comes standard:

while x()
   y()

However, the following¹ doesn't work:

do
  y()
while x()

And this is simply sugar for the first example:

y() while x()

Does CoffeeScript come with a built-in loop that executes at least once?

¹As an aside, do is a keyword — it's used to call anonymous functions.

分享到QQ

分享到微博

如果你对这篇内容有疑问，欢迎到本站社区发帖提问参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。

发布评论

需要登录才能够评论，你可以免费注册一个本站的账号。

红玫瑰 2024-11-15 15:37:05

CoffeeScript 文档说：

CoffeeScript 提供的唯一低级循环是 while 循环。

我不知道至少执行一次的内置循环，所以我想替代方案是

loop
  y()
  break if x()

The CoffeeScript documentation says:

The only low-level loop that CoffeeScript provides is the while loop.

I don't know of a built-in loop that executes at least once, so I guess the alternative is

loop
  y()
  break if x()

回复收藏 0 原文

独留℉清风醉 2024-11-15 15:37:05

我知道这个答案很旧，但自从我通过谷歌进入这里，我想其他人也可能会这样。

要在 CoffeeScript 中构建等效的 do...while 循环，我认为这种语法模拟它是最好、最简单的，并且非常易读：

while true
   # actions here
   break unless # conditions here

I know that this answer is very old, but since I entered here via Google, I thought someone else might as well.

To construct a do...while loop equivalent in CoffeeScript I think that this syntax emulates it the best and easiest and is very readable:

while true
   # actions here
   break unless # conditions here

回复收藏 0 原文

柳若烟 2024-11-15 15:37:05

您的猜测是正确的：CoffeeScript 中没有等效的 do-while 。所以你通常会写

y()
y() while x()

如果你发现自己经常这样做，你可以定义一个辅助函数：

doWhile = (func, condition) ->
  func()
  func() while condition()

Your guess is correct: There is no do-while equivalent in CoffeeScript. So you'd typically write

y()
y() while x()

If you find yourself doing this often, you might define a helper function:

doWhile = (func, condition) ->
  func()
  func() while condition()

回复收藏 0 原文

北方。的韩爷 2024-11-15 15:37:05

我发现这可以通过短路条件来完成：

flag = y() while not flag? or x()

I found this could be accomplished through a short circuit conditional:

flag = y() while not flag? or x()

回复收藏 0 原文

东走西顾 2024-11-15 15:37:05

我一直在研究一个项目，我只是强制条件在循环结束时进行评估，然后在开始时终止。

# set the 'do' variable to pass the first time
do = true
while do

  # run your intended code
  x()

  # evaluate condition at the end of
  # the while code block
  do = condition

# continue code

它不是很优雅，但它确实阻止您仅为 while 代码块定义一个新函数并运行它两次。通常有一种方法可以围绕 do...while 语句进行编码，但对于那些无法做到这一点的情况，您可以有一个简单的解决方案。

I've been working on a project where I simply force the condition to evaluate at the end of the loop, then terminate at the beginning.

# set the 'do' variable to pass the first time
do = true
while do

  # run your intended code
  x()

  # evaluate condition at the end of
  # the while code block
  do = condition

# continue code

It's not very elegant, but it does keep you from defining a new function just for your while code block and running it twice. There generally is a way to code around the do...while statements, but for those time that you can't you have a simple solution.

回复收藏 0 原文

~没有更多了~