ruby新手问一个简单的问题，看不懂。

[防空洞]

# Linked list example
class MyElem
# object initializer called from Class#new
def initialize(item)
# @variables are instance variable, no declaration needed
@data = item
@succ = nil
end

def data
@data
end

def succ
@succ
end

# the method invoked by ``obj.data = val''
def succ=(new)
@succ = new
end
end

class MyList
def add_to_list(obj)
elt = MyElem.new(obj)
if @head
@tail.succ = elt
else
@head = elt
end
@tail = elt
end

def each
elt = @head
while elt
yield elt
elt = elt.succ
end
end

# the method to convert object into string.
# redefining this will affect print.
def to_s
str = "<MyList:\n";
for elt in self
# short form of ``str = str + elt.data.to_s + "\n"''
str += elt.data.to_s + "\n"
end
str += ">"
str
end
end

class Point
def initialize(x, y)
@x = x; @y = y
self
end

def to_s
sprintf("%d@%d", @x, @y)
end
end

# global variable name starts with `$'.
$list1 = MyList.new
$list1.add_to_list(10)
$list1.add_to_list(20)
$list1.add_to_list(Point.new(2, 3))
$list1.add_to_list(Point.new(4, 5))
$list2 = MyList.new
$list2.add_to_list(20)
$list2.add_to_list(Point.new(4, 5))
$list2.add_to_list($list1)

# parenthesises around method arguments can be ommitted unless ambiguous.
print "list1:\n", $list1, "\n"
print "list2:\n", $list2, "\n"


请问MyList的dd_to_list(obj)如何理解

[wuguanlin]

在MyList类里加了一个dd_to_list()方法

[防空洞]

只是这个方法怎么实现的linked list啊，元素能不停地往里加。

[wuguanlin]

$list1 = MyList.new
$list1.add_to_list(10)
$list1.add_to_list(20)
$list1.add_to_list(Point.new(2, 3))
$list1.add_to_list(Point.new(4, 5))
$list2 = MyList.new
$list2.add_to_list(20)
$list2.add_to_list(Point.new(4, 5))
$list2.add_to_list($list1)
＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
这里不是在不停的加入元素吗？

[peswe]

def add_to_list(obj) 
    elt = MyElem.new(obj) 
    if @head 
      @tail.succ = elt 
    else 
      @head = elt 
    end 
    @tail = elt 
  end 

注意上面添加的是MyElem的实例对象，清楚了这点，就不难理解了
MyElem的实例对象都有data和succ方法,其中succ指向下一个元素，这样便可以串起来了

[kunhua15]

这样也可以？不是吧

[lliuxingyu]

菜菜，不懂！