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In [41]: class CounterList(list):
   ....:     def __init__(self, *args):
   ....:         super(CounterList, self).__init__(*args)
   ....:         self.counter = 0
   ....:     def __getitem__(self, index):
   ....:         self.counter += 1
   ....:         return super(CounterList, self).__getitem__(index)
   ....: 

In [42]: cl = CounterList(range(10))

In [43]: cl
Out[43]: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

In [44]: cl.reverse()

In [45]: cl
Out[45]: [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]

In [46]: del cl[3:6]

In [47]: cl
Out[47]: [9, 8, 7, 3, 2, 1, 0]

In [48]: cl.counter
Out[48]: 3

In [49]: cl[4] + cl[2]
Out[49]: 9

In [50]: cl.counter
Out[50]: 5

Code: Alles auswählen

[GCC 4.2.1 (Apple Inc. build 5646)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> class CounterList(list):
...     def __init___(self, *args):
...         super(CounterList, self).__init__(*args)
...         self.counter = 0
...     def __getitem__(self, index):
...         self.counter += 1
...         return super(CounterList, self).__getitem__(index)
... 
>>> cl = CounterList(range(10))
>>> cl
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> cl.reverse()
>>> cl
[9, 8, 7, 6, 5, 4, 3, 2, 1, 0]
>>> del cl[3:6]
>>> cl
[9, 8, 7, 3, 2, 1, 0]
>>> cl.counter
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'CounterList' object has no attribute 'counter'
>>>