为什么我使用注入重构的 ruby 不起作用？

发布于 2024-09-25 04:45:51 字数 1198 浏览 7 评论 0原文

我尝试进行一些重构以将每个块转换为注入，但它不起作用，我不明白为什么。

这是在重构之前有效的代码：

class String
  # Build the word profile for the given word. The word profile is an array of
  # 26 integers -- each integer is a count of the number of times each letter
  # appears in the word. 
  #
  def profile
    profile = Array.new(26) { 0 }
    self.downcase.split(//).each do |letter|
      # only process letters a-z
      profile[letter.ord - 'a'.ord] += 1 unless letter.ord > 'z'.ord
    end
    profile
  end
end

这是我的重构不起作用：

class String
  # Build the word profile for the given word. The word profile is an array of
  # 26 integers -- each integer is a count of the number of times each letter
  # appears in the word. 
  #
  def profile
    self.downcase.split(//).inject(Array.new(26) {0}) do |profile, letter|
      # only process letters a-z
      profile[letter.ord - 'a'.ord] += 1 unless letter.ord > 'z'.ord 
    end
  end
end

当我尝试执行重构的方法时，我得到了

`block in profile': undefined method `[]=' for 1:Fixnum (NoMethodError)

如果我理解正确的话，它不喜欢配置文件对象上的数组引用运算符我的重构版本，这意味着传递给注入的初始化程序不起作用。这种理解正确吗？如果是这样，为什么不呢？

谢谢！

原文

I tried to do some refactoring to convert an each block into an inject, but it didn't work and I don't understand why.

Here's the code that works before refactoring:

class String
  # Build the word profile for the given word. The word profile is an array of
  # 26 integers -- each integer is a count of the number of times each letter
  # appears in the word. 
  #
  def profile
    profile = Array.new(26) { 0 }
    self.downcase.split(//).each do |letter|
      # only process letters a-z
      profile[letter.ord - 'a'.ord] += 1 unless letter.ord > 'z'.ord
    end
    profile
  end
end

and here's my refactor that doesn't work:

class String
  # Build the word profile for the given word. The word profile is an array of
  # 26 integers -- each integer is a count of the number of times each letter
  # appears in the word. 
  #
  def profile
    self.downcase.split(//).inject(Array.new(26) {0}) do |profile, letter|
      # only process letters a-z
      profile[letter.ord - 'a'.ord] += 1 unless letter.ord > 'z'.ord 
    end
  end
end

When I try and execute the refactored method I'm getting

`block in profile': undefined method `[]=' for 1:Fixnum (NoMethodError)

If I understand that correctly, it's doesn't like the array reference operator on the profile object in my refactored version, which implies that the initialiser passed to inject isn't working. Is that understanding correct? And if so, why not?

Thanks!

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。

睫毛上残留的泪 2024-10-02 04:45:51

[]= 方法返回分配的值，因此下一次迭代中 profile 的值将为 1（因为它是上一次迭代的值）。为了获得您想要的行为，您必须执行以下操作：

self.downcase.split(//).inject(Array.new(26) {0}) do |profile, letter|
  # only process letters a-z
  profile[letter.ord - 'a'.ord] += 1 unless letter.ord > 'z'.ord 
  profile
end

或

self.downcase.split(//).inject(Array.new(26) {0}) do |profile, letter|
  # only process letters a-z
  profile.tap { profile[letter.ord - 'a'.ord] += 1 unless letter.ord > 'z'.ord }
end

The []= method returns the assigned value, so the value of profile in the next iteration will be 1 (since it's the value of the last iteration). In order to get the behavior you want, you'll have to do:

self.downcase.split(//).inject(Array.new(26) {0}) do |profile, letter|
  # only process letters a-z
  profile[letter.ord - 'a'.ord] += 1 unless letter.ord > 'z'.ord 
  profile
end

self.downcase.split(//).inject(Array.new(26) {0}) do |profile, letter|
  # only process letters a-z
  profile.tap { profile[letter.ord - 'a'.ord] += 1 unless letter.ord > 'z'.ord }
end

回复收藏 0 原文

~没有更多了~