带有自定义_getattr和_setattr的Python深度复制__
我实现了一个类,它可以区分一组固定的实例属性(我们称之为元属性)和一组任意的其他实例属性 它有自定义的带有自定义_getattr和_setattr的Python深度复制__,python,python-2.7,copy,getattr,Python,Python 2.7,Copy,Getattr,我实现了一个类,它可以区分一组固定的实例属性(我们称之为元属性)和一组任意的其他实例属性 它有自定义的\uuuuu getattr\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu class MyClass(object): def __init__(self, meta1, meta2, **other_attr): super(MyClass, self).__
\uuuuu getattr\uuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuuu
class MyClass(object):
def __init__(self, meta1, meta2, **other_attr):
super(MyClass, self).__setattr__('meta1', meta1)
super(MyClass, self).__setattr__('meta2', meta2)
super(MyClass, self).__setattr__('params', {})
self.params = {key: other_attr[key] for key in other_attr}
# this is called when default lookup finds nothing
def __getattr__(self, key):
print('__getattr__({})'.format(key))
try:
return self.params[key]
except KeyError:
raise AttributeError(key)
# this is called always
def __setattr__(self, key, value):
print('__setattr__({}, {})'.format(key, value))
if key in self.__dict__:
super(MyClass, self).__setattr__(key, value)
else:
self.params[key] = value
这很好,所有元属性直接进入实例的\uu dict\uu
,而所有其他属性进入参数
字典:
obj1 = MyClass(meta1 = 'foo', meta2 = 'bar', x=1, y=2, z=3)
obj1.w = 4
print(obj1.__dict__)
输出:
除非我尝试deepcopy
我的对象时,它会做一些奇怪的事情:
import copy
obj1 = MyClass(meta1='foo', meta2='bar', x=1, y=2, z=3)
obj2 = copy.deepcopy(obj1)
输出:
最后,它确实创建了一个副本,但为什么它要调用这么多的\uuuuuGetAttr\uuuuuuuuuuuuuuuuuuuuu
你应该这样做
return super().__getattribute__('params')[key]
这会导致递归查找(请记住,obj2
不是通过初始化的
你应该这样做
return super().__getattribute__('params')[key]
谢谢,成功了。但为什么它不会导致无限递归,而是在某个点停止?@spiderface,我得到RuntimeError:调用Python对象时超过了最大递归深度。也许您尝试了一个版本,但异常句柄略有不同,这很奇怪。我还发现,我不必从\uuu getattribute\uuu
返回值,只需调用它,然后返回return self.params[key]
就足够了。对我来说,从python 2.7切换到python 3.7是个问题。getattribute解决了这个问题。谢谢,成功了。但为什么它不会导致无限递归,而是在某个点停止?@spiderface,我得到RuntimeError:调用Python对象时超过了最大递归深度。也许您尝试了一个版本,但异常句柄略有不同,这很奇怪。我还发现,我不必从\uuu getattribute\uuu
返回值,只需调用它,然后返回return self.params[key]
就足够了。对我来说,从python 2.7切换到python 3.7是个问题。getattribute解决了这个问题。
return self.params[key]
return super().__getattribute__('params')[key]