您可以总是子类化list并添加“冻结”标志，该标志将阻止__setitem__执行任何操作：
class freezablelist(list):
def __init__(self,*args,**kwargs):
list.__init__(self, *args)
self.frozen = kwargs.get('frozen', False)
def __setitem__(self, i, y):
if self.frozen:
raise TypeError("can't modify frozen list")
return list.__setitem__(self, i, y)
def __setslice__(self, i, j, y):
if self.frozen:
raise TypeError("can't modify frozen list")
return list.__setslice__(self, i, j, y)
def freeze(self):
self.frozen = True
def thaw(self):
self.frozen = False
然后玩：
>>> from freeze import freezablelist as fl
>>> a = fl([1,2,3])
>>> a[1] = 'chicken'
>>> a.freeze()
>>> a[1] = 'tuna'
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "freeze.py", line 10, in __setitem__
raise TypeError("can't modify frozen list")
TypeError: can't modify frozen list
>>> a[1:1] = 'tuna'
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "freeze.py", line 16, in __setslice__
raise TypeError("can't modify frozen list")
TypeError: can't modify frozen list
>>>
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