Shallowly discuss the special methods of s 0en class s s 1en__ and s 2en__

For a slightly convoluted example, step tracing with the PyScripter debugger lets you see the details of the image structure.

Change the original by 1, using the ready-made model of s 5en__ in the undefined subobject property.

## encoding:utf-8
"""
 This class inherits object, object is Python The smallest unit can be in Python the ">>>" The console with dir(objct) or dir (__builtins__.object) The command looks at its properties, as you can see __setattr__, __new__... They are python You can have properties that any object in the dir(1) and dir(int) Check it out. You can see more. Here, 1 As a 1 Two instantiated int Object appears. And these __xxx__ What are properties good for? In the following code, we'll see __getitem__ and __setitem__ What's the use of  ( These two properties are dict Very important in the object )
"""

class WPUnit(object):
  def __init__(self):
    self._res={}

def __setitem__(self,key,val):
  self._res[key]=val

def __getitem__(self,key):
  if self._res.has_key(key):
    return self._res[key]
  else:
    r=WPUnit()
    self.__setitem__(key,r)
    return r

a=WPUnit()
a['a']['b']['c']['d']['e']['f']['g']=5
print a['a']['b']['c']['d']['e']['f']['g']

>>> class testsetandget: 
  kk = {}; 
  def __getitem__(self, key): 
    return self.kk[key]; 
  def __setitem__(self, key, value): 
    self.kk[key] = value; 
     
>>> a = testsetandget() 
>>> a['first'] = 1 
>>> a['first'] 
1 
>>> a.__setitem__('second', 2) 
>>> a.__getitem__('second') 
2 
>>> a['second'] 
2 
>>>