参考 @sr2222 的建议,这是我的尝试。(我将使用一个没有语法糖的装饰器):
import sys
_pyversion = sys.version_info[0]
def callback_method(func):
def notify(self,*args,**kwargs):
for _,callback in self._callbacks:
callback()
return func(self,*args,**kwargs)
return notify
class NotifyList(list):
extend = callback_method(list.extend)
append = callback_method(list.append)
remove = callback_method(list.remove)
pop = callback_method(list.pop)
__delitem__ = callback_method(list.__delitem__)
__setitem__ = callback_method(list.__setitem__)
__iadd__ = callback_method(list.__iadd__)
__imul__ = callback_method(list.__imul__)
if _pyversion < 3:
__setslice__ = callback_method(list.__setslice__)
__delslice__ = callback_method(list.__delslice__)
def __getslice__(self,*args):
return self.__class__(list.__getslice__(self,*args))
def __getitem__(self,item):
if isinstance(item,slice):
return self.__class__(list.__getitem__(self,item))
else:
return list.__getitem__(self,item)
def __init__(self,*args):
list.__init__(self,*args)
self._callbacks = []
self._callback_cntr = 0
def register_callback(self,cb):
self._callbacks.append((self._callback_cntr,cb))
self._callback_cntr += 1
return self._callback_cntr - 1
def unregister_callback(self,cbid):
for idx,(i,cb) in enumerate(self._callbacks):
if i == cbid:
self._callbacks.pop(idx)
return cb
else:
return None
if __name__ == '__main__':
A = NotifyList(range(10))
def cb():
print ("Modify!")
cbid = A.register_callback(cb)
A.append('Foo')
A += [1,2,3]
A *= 3
A[1:2] = [5]
del A[1:2]
def cb2():
print ("Modify2")
A.register_callback(cb2)
print ("-"*80)
A[5] = 'baz'
print ("-"*80)
A.unregister_callback(cbid)
A[5] = 'qux'
print ("-"*80)
print (A)
print (type(A[1:3]))
print (type(A[1:3:2]))
print (type(A[5]))
这个好处在于如果你发现自己忘记考虑了某种特定的方法,只需添加1行代码即可。 (例如,我直到现在才想起了__iadd__和__imul__ :))
编辑
我稍微更新了一下代码,使其兼容py2k和py3k。此外,切片创建与父对象相同类型的新对象。请继续挑毛病,这样我就可以让它变得更好。这似乎是一个非常不错的东西...
__iadd__
和__imul__
:). 我刚刚添加了它们。 - mgilson