[英]python class inherit affects property?
I met a weird issue. 我遇到了一个奇怪的问题。 please see the code I paste below. 请参阅下面粘贴的代码。 in myclass I have a @property datef. 在myclass中,我有一个@property datef。 I can set get the property; 我可以设置获取属性; but when I make myclass inherit from mybase, I cannot set the property any more. 但是当我使myclass从mybase继承时,我无法再设置该属性。 Why? 为什么?
class mybase(object):
pass
class myclass(mybase):
@property
def dataf(self): return 1
var = myclass()
print var.dataf
var.dataf = 33
print var.__dict__
You need to define property getter and setter: 您需要定义属性获取器和设置器:
class mybase(object):
pass
class myclass(mybase):
def dataf_get(self): return getattr(self, "_data_f", None)
def dataf_set(self, value): self._data_f = value
dataf = property(dataf_get, dataf_set)
var = myclass()
print var.dataf
>> None
var.dataf = 33
print var.dataf
>> 33
print var.__dict__
>> {'_data_f': 33}
The @property decorator only works properly with new-style classes. @property装饰器仅适用于新样式的类。
If you tried 如果你尝试过
class myclass:
@property
def dataf(self): return 1
then myclass
is an old-style class, so don't expect @property to work properly. 那么myclass
是一个老式的类,因此不要期望@property正常工作。
When instead you make myclass
a subclass of mybase
which in turn inherits from object
, you are making myclass
a new-style class. 相反,当您将myclass
mybase
的子类,而mybase
的子类又继承自object
,您使myclass
成为新样式的类。 Now @property works properly. 现在@property可以正常工作。
Now you need to define a setter if you wish to be able to set the property. 现在,如果您希望能够设置属性,则需要定义一个setter。
class mybase(object):
pass
class myclass(mybase):
@property
def dataf(self): return 1
@dataf.setter
def dataf(self, value):
self._dataf = value
var = myclass()
print var.dataf
var.dataf = 33
print var.__dict__
yields 产量
1
{'_dataf': 33}
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