动态创建Struct实例

Pair = Struct.new(:token, :word)
first_word = Pair.new("direction", "north")
second_word = Pair.new("verb", "go")
#定义一个数组,保存这个新建的Struct
sentence = [first_word, second_word]

p sentence
# => [#<struct Pair token="direction", word="north">, #<struct Pair token="verb", word="go">]
p sentence[0]
# => #<struct Pair token="direction", word="north">
#直接使用句号操作符来显示Struct中的数据
p sentence[0].token,sentence[0].word
# "direction"
# "north"
#或者使用symbol的方式来输出,结果相同
p sentence[0][:token],sentence[0][:word]
# "direction"
# "north"

再来一个实例

# encoding: UTF-8
# t=Struct.new('person',:name,:age)
#算是元编程?
t=Struct.new('Topic',:name,:replies) #Topic一定得是大写,包括类也是一样,强制性的约定
p t     # => Struct::Topic
t1=t.new('first',['good','not bad!','nice!'])
t2=t.new('second',['不错','好','OK'])
topics=[t1,t2]
p topics
    #中文使用p来输出的时候显示的是其unicode编码
    # => [#<struct Struct::Topic name="first",     replies=["good", "not bad!", "nice!"]>, 
    #<struct Struct::Topic name="second", replies=["\u4E0D\u9519", "\u597D", "OK"]>]
p topics[0].name
    # => "first" 正是动态性的体现,只要有name就能显示
p topics[1].replies
    # => ["\u4E0D\u9519", "\u597D", "OK"]