当用[..]（切片）方法引用数组时，Ruby是否创建副本？ [英] Does Ruby create a copy when referencing an array with its [..] (slice) method?

问题描述

我想在数组的一个切片上循环。我基本上有两个主要选择。

I want to loop on a slice of an array. I have basically two main options.

ar.each_with_index{|e,i|
   next if i < start_ind
   break if i > end_ind
   foo(e)
   #maybe more code...
}

另一个我认为更优雅的选择是运行：

Another option, which I think is more elegant, would be to run:

ar[start_ind..end_ind].each{|e|
   foo(e)
   #maybe more code...
}

我担心的是Ruby可能在后台创建一个巨大的数组并进行大量内存分配。还是有某种更智能的玩法不会创建副本？

My concern is Ruby potentially creating a huge array under the hood and doing a lot of memory allocation. Or is there something "smarter" at play that does not create a copy?

推荐答案

您可以执行一个索引值循环。 ..不如第二种解决方案那么优雅，但经济。

You could do a loop of index values... not as elegant as your second solution but economical.

(start_ind..end_ind).each do |index|
  foo(ar[index])
  # maybe more code
end

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