如何创建私有类方法？ [英] How to create a private class method?

问题描述

这种创建私有类方法的方法是如何工作的：

How come this approach of creating a private class method works:

class Person

  def self.get_name
    persons_name
  end

  class << self

    private

    def persons_name
      "Sam"
    end
  end
end

puts "Hey, " + Person.get_name
puts "Hey, " + Person.persons_name  #=> raises "private method `persons_name' called for Person:Class (NoMethodError)"

但这不是：

class Person

  def self.get_name
    persons_name
  end

  private

  def self.persons_name
    "Sam"
  end
end

puts "Hey, " + Person.get_name
puts "Hey, " + Person.persons_name

推荐答案

私有 self ），则c> 似乎不起作用。您可以使用 private_class_method 将类方法定义为私有（或您所描述的）。

private doesn't seem to work if you are defining a method on an explicit object (in your case self). You can use private_class_method to define class methods as private (or like you described).

class Person
  def self.get_name
    persons_name
  end

  def self.persons_name
    "Sam"
  end

  private_class_method :persons_name
end

puts "Hey, " + Person.get_name
puts "Hey, " + Person.persons_name

或者（在ruby 2.1+中），由于方法定义返回方法名称的符号，因此您也可以按以下方式使用它：

Alternatively (in ruby 2.1+), since a method definition returns a symbol of the method name, you can also use this as follows:

class Person
  def self.get_name
    persons_name
  end

  private_class_method def self.persons_name
    "Sam"
  end
end

puts "Hey, " + Person.get_name
puts "Hey, " + Person.persons_name

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