Rails 对象#空白?与字符串#空?困惑

问题描述

Rails 文档 有 对象#blank?

如果对象为 false、空或空白字符串，则该对象为空.例如，"、"、nil、[] 和 {} 为空.

但是那个方法的来源是这样的:

But the source for that method is like this:

# File activesupport/lib/active_support/core_ext/object/blank.rb, line 12
def blank?
    respond_to?(:empty?) ? empty? : !self
end

现在，当我打开方便的小命令行并输入 ruby -e 'p " ".empty?' 时，它返回 false.这意味着 Rails 应该说这是一个空白值，而这显然不是.但！我打开我的 rails 控制台 并输入 " ".empty? 并像我之前的直接命令行一样得到 false.但是，我输入".blank?就像 Rails 答应我的那样，我做到了.

Now, when I open my handy little command line and type ruby -e 'p " ".empty?' it returns false. That means that Rails should say this is a blank value when it's clearly not. But! I open my rails console and I type " ".empty? and get false like my earlier straight command line. But, I type " ".blank? and I get true like Rails promises me.

在理解 Rails 的 blank? 方法如何与 String 的 empty? 方法一起工作时，我缺少什么?

What am I missing in understanding how Rails' blank? method works with the empty? method of String?

推荐答案

Rails 在记录其 blank? 方法方面有点棘手.尽管 Object#blank? 声称也检测空格字符串，但它是通过 String#blank? 实现的，以处理空格情况和 Object#blank?代码> 来捕捉一般情况.(空白? 也定义在其他一些类上，以节省时间.)

Rails is kinda tricky in how it documents its blank? method. Even though Object#blank? claims to also detect whitespace strings, it is implemented with String#blank? to handle the whitespace case and Object#blank? to catch the generic case. (blank? is defined on a few other classes, too, to save time.)

activesupport/lib/active_support/core_ext/object/blank.rb，第 66 行:

class String
  def blank?
    self !~ /\S/
  end
end

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