Question

send可用于调用公共方法和私有方法。

示例：

class Demo
  def public_method
    p "public_method" 
  end

  private

  def private_method
    p "private_method" 
  end
end

Demo.new.send(:private_method)
Demo.new.send(:public_method)

然后使用public_send的地点和原因？

Answer 1

当您想要动态推断方法名称并调用它时，请使用public_send，但仍然不希望出现封装问题。

换句话说，public_send只会直接模拟方法的调用，无需解决。混合封装和元编程很有用。

示例：

class MagicBox
  def say_hi
    puts "Hi"
  end

  def say_bye
    puts "Bye"
  end

  private

  def say_secret
    puts "Secret leaked, OMG!!!"
  end

  protected

  def method_missing(method_name)
    puts "I didn't learn that word yet :\\"
  end
end

print "What do you want met to say? "
word = gets.strip

box = MagicBox.new
box.send("say_#{word}")        # => says the secret if word=secret
box.public_send("say_#{word}") # => does not say the secret, just pretends that it does not know about it and calls method_missing.

当输入为hi且secret时，这是输出：

What do you want met to say? hi
=> Hi
=> Hi

What do you want met to say? secret
=> Secret leaked, OMG!!!
=> I didn't learn that word yet :\\

如您所见，send将调用私有方法，因此会出现安全/封装问题。而public_send只会在公共时调用该方法，否则会发生正常行为（如果被覆盖则调用method_missing，或者引发NoMethodError）。

何时在ruby中使用send和public_send方法？

1 个答案: