初学,请帮忙看一下...

初学,请帮忙看一下...

class Person
 def initialize(name,age=20)
  @name = name
  @age = age
  @motherLand ="I am a Chinese"
 end
 def talk
  puts "I am [email=#{@name},my]#{@name},my[/email] age is [email=#{@age.php?name=to_s" onclick="tagshow(event)" class="t_tag">to_s]#{@age.php?name=to_s" onclick="tagshow(event)" class="t_tag">to_s[/email]}"
  puts @motherLand 
 end
end

随便定义一个Person,保存为文件person.rb
在main.rb中
p = Person.new("zhang", 20)
p.talk

提示:G:\ROR\Person\lib\main.rb:6:in `const_missing': uninitialized constant Person (NameError)
   from G:\ROR\Person\lib\main.rb:6
为什么???

ps:把Person定义在main.rb中,就可以运行了...
刚学,对ruby的机制不大懂...所以可能问得有点弱智...
def talk
  puts "I am #{@name},my age is #{@age.to_s}"
  puts @motherLand 
 end
talk是这样定义的...
怎么没有人帮着解答啊....
貌似在main.rb要加
require 'person.rb'
还真的是这样...谢谢啊...