看来看来，还是以下这个实现最优雅。。

其它的，要么NODE冗余，要么初始化丑陋。。。

#!/usr/bin/env python
# -*- coding: utf-8 -*-


class Node:
    
  def __init__(self, initdata):
    self.__data = initdata
    self.__next = None
    
  def getData(self):
    return self.__data

  def getNext(self):
    return self.__next

  def setData(self, newdata):
    self.__data = newdata
    
  def setNext(self, newnext):
    self.__next = newnext

    
class SinCycLinkedlist:
    
  def __init__(self):
    self.head = Node(None)
    self.head.setNext(self.head)
    
  def add(self, item):
    temp = Node(item)
    temp.setNext(self.head.getNext())
    self.head.setNext(temp)
    
  def remove(self, item):
    prev = self.head
    while prev.getNext() != self.head:
      cur = prev.getNext()
      if cur.getData() == item:
        prev.setNext(cur.getNext())
      prev = prev.getNext()
      
  def search(self, item):
      
    cur = self.head.getNext()
    while cur != self.head:
      if cur.getData() == item:
        return True
      cur = cur.getNext()
    return False

  def empty(self):
    return self.head.getNext() == self.head
  def size(self):
    count = 0
    cur = self.head.getNext()
    while cur != self.head:
      count += 1
      cur = cur.getNext()
    return count

if __name__ == '__main__':
  s = SinCycLinkedlist()
  print('s.empty() == %s, s.size() == %s' % (s.empty(), s.size()))
  s.add(19)
  s.add(86)
  print('s.empty() == %s, s.size() == %s' % (s.empty(), s.size()))
  print('86 is%s in s' % ('' if s.search(86) else ' not',))
  print('4 is%s in s' % ('' if s.search(4) else ' not',))
  print('s.empty() == %s, s.size() == %s' % (s.empty(), s.size()))
  s.remove(19)
  print('s.empty() == %s, s.size() == %s' % (s.empty(), s.size()))