都做吗?有吗?保证短路评估? [英] Do all? and any? guarantee short-circuit evaluation?

问题描述

在 pry 和 irb 中测试一些代码，我得到以下结果:

Testing out some code in both pry and irb, I get the following results:

[1] pry(main)> a = [1, 3, 5, 7, 0]
=> [1, 3, 5, 7, 0]
[2] pry(main)> a.any? {|obj| p obj; 3 / obj > 1}
1
=> true
[3] pry(main)> a.all? {|obj| p obj; 3 / obj > 1}
1
3
=> false

在 [2] 和 [3] 我看到似乎有短路评估会尽快中止迭代，但这是有保证的行为吗?阅读文档没有提到这种行为.我意识到我可以使用 inject 代替，因为它会遍历所有内容，但我很想知道官方的 Ruby 视图是什么.

In [2] and [3] I see that there appears to be short-circuit evaluation that aborts the iteration as soon as possible, but is this guaranteed behaviour? Reading the documentation there is no mention of this behaviour. I realise that I can use inject instead as that will iterate over everything, but I'm interested in finding out what the official Ruby view is.

推荐答案

是.

在 Ruby 标准的最终草案中，all? 定义如下:

In the final draft of the Ruby standard, all? is defined as such:

1. 在接收器上调用each方法
2. 对于方法 each 产生的每个元素 X:

1. Invoke the method each on the receiver
2. For each element X which the method each yeilds:

1. 如果给出了块，则以 X 作为参数调用块.如果这个调用返回一个虚假的对象，return false.
2. 如果块没有给出，并且 X 是一个虚假的对象，返回 false.

返回true.

注意步骤 2 中的 return 这个词.这保证了短路评估.any? 的定义类似.然而，该标准仍然是一个草案，我不知道哪些 Ruby 实现(如果有)旨在符合标准.

Note the word return in step 2. This guarantees short circuit evaluation. any? is defined similarly. However the standard is still a draft and I don't know which Ruby implementations (if any) aim to be standards-compliant.

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