利用ctypes实现array,迭代出错

1. import ctypes
   
2. class  Array(object):
   
3.     """docstring for  a"""
   
4.     def __init__(self, size):
   
5.         assert size > 0 and type(size) == int,'Array size must be >0 and a integer'
   
6.         self._size = size
   
7.         PyArrayType = ctypes.py_object*self._size
   
8.         self._elements = PyArrayType()
   
9.         self.clear(None)
   
10.     def __len__(self):
    
11.             return self._size
    
12.     def __getitem__(self,index):
    
13.             assert index >= 0 and index < self._size ,'Array sunscript out of range'
    
14.             return self._elements[index]
    
15.     def __setitem__(self,index,value):
    
16.             assert index >= 0 and index < self._size ,'Array sunscript out of range'
    
17.             self._elements[index] = value
    
18.     def clear(self,value):
    
19.             for i in range(self._size):
    
20.                 self._elements[i] = value
    
21.     def __iter__(self):
    
22.             return _ArrayIterator(self._elements)
    
23. class _ArrayIterator(object):
    
24.     """docstring for _ArrayIterator"""
    
25.     def __init__(self, theArray):
    
26.         self._arrayRef = theArray
    
27.         self._curNdx = 0
    
28.     def __iter__(self):
    
29.         return self
    
30.     def __next__(self):
    
31.         if self._curNdx >= 0 and self._curNdx < len(self._arrayRef):
    
32.             entry = self._arrayRef[self._curNdx]
    
33.             self._curNdx += 1
    
34.             return entry
    
35.         else:
    
36.             raise StopIteration

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当进行以下操作时：

1. a = Array(5)       
   
2. a.clear(5)
   
3. for i  in a:
   
4.     print i

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出现iter() returned non-iterator of type '_ArrayIterator'
的报错，请大神指点一下