Ruby 自身和 puts

Question

如果 self 是 ruby​​ 中的默认接收者，并且您在实例方法定义中调用“puts”，那么该调用的接收者是对象的实例吗？

例如

    class MyClass
      attr_accessor :first_name, :last_name, :size

      # initialize, etc (name = String, size = int)

      def full_name
        fn = first_name + " " + last_name 
        # so here, it is implicitly self.first_name, self.last_name
        puts fn 
        # what happens here?  puts is in the class IO, but myClass 
        # is not in its hierarchy (or is it?)
        fn
      end
    end

Answer 1

绝对的，当前对象就是这里方法调用的接收者。之所以可行，是因为 Kernel 模块定义了一个 puts方法并混入Object ，这是每个 Ruby 类的隐式根类。证明:

class MyClass
  def foo 
    puts "test"
  end
end

module Kernel
  # hook `puts` method to trace the receiver
  alias_method :old_puts, :puts
  def puts(*args)
    p "puts called on %s" % self.inspect
    old_puts(*args)
  end
end

MyClass.new.foo 

这会打印出 puts called from #<MyClass:0x00000002399d40> , 所以 MyClass实例是接收者。