我有一个对象 (Person
),它有多个子对象 (Pet, Residence
) 作为属性。我希望能够像这样动态设置这些子对象的属性:
class Person(object):
def __init__(self):
self.pet = Pet()
self.residence = Residence()
class Pet(object):
def __init__(self,name='Fido',species='Dog'):
self.name = name
self.species = species
class Residence(object):
def __init__(self,type='House',sqft=None):
self.type = type
self.sqft=sqft
if __name__=='__main__':
p=Person()
setattr(p,'pet.name','Sparky')
setattr(p,'residence.type','Apartment')
print p.__dict__
目前我得到了错误的输出:{'pet': <__main__.Pet object at 0x10c5ec050>, 'residence': <__main__.Residence object at 0x10c5ec0d0>, 'pet.name': 'Sparky', 'residence.type': 'Apartment'}
如您所见,而不是设置 name
Pet
上的属性Person
的子对象, 新属性 pet.name
创建于 Person
.
我无法指定
person.pet
至setattr()
因为不同的子对象将通过相同的方法设置,如果/当找到相关键时,该方法会解析一些文本并填充对象属性。有没有一种简单/内置的方法来完成这个?
或者我可能需要编写一个递归函数来解析字符串并调用
getattr()
多次,直到找到必要的子对象,然后调用setattr()
在那个找到的子对象上?
最佳答案
您可以使用 functools.reduce
:
import functools
def rsetattr(obj, attr, val):
pre, _, post = attr.rpartition('.')
return setattr(rgetattr(obj, pre) if pre else obj, post, val)
# using wonder's beautiful simplification: https://stackoverflow.com/questions/31174295/getattr-and-setattr-on-nested-objects/31174427?noredirect=1#comment86638618_31174427
def rgetattr(obj, attr, *args):
def _getattr(obj, attr):
return getattr(obj, attr, *args)
return functools.reduce(_getattr, [obj] + attr.split('.'))
rgetattr
和 rsetattr
是 getattr
和 setattr
的直接替换,
它还可以处理带点的 attr
字符串。
import functools
class Person(object):
def __init__(self):
self.pet = Pet()
self.residence = Residence()
class Pet(object):
def __init__(self,name='Fido',species='Dog'):
self.name = name
self.species = species
class Residence(object):
def __init__(self,type='House',sqft=None):
self.type = type
self.sqft=sqft
def rsetattr(obj, attr, val):
pre, _, post = attr.rpartition('.')
return setattr(rgetattr(obj, pre) if pre else obj, post, val)
def rgetattr(obj, attr, *args):
def _getattr(obj, attr):
return getattr(obj, attr, *args)
return functools.reduce(_getattr, [obj] + attr.split('.'))
if __name__=='__main__':
p = Person()
print(rgetattr(p, 'pet.favorite.color', 'calico'))
# 'calico'
try:
# Without a default argument, `rgetattr`, like `getattr`, raises
# AttributeError when the dotted attribute is missing
print(rgetattr(p, 'pet.favorite.color'))
except AttributeError as err:
print(err)
# 'Pet' object has no attribute 'favorite'
rsetattr(p, 'pet.name', 'Sparky')
rsetattr(p, 'residence.type', 'Apartment')
print(p.__dict__)
print(p.pet.name)
# Sparky
print(p.residence.type)
# Apartment
关于python - getattr 和 setattr 在嵌套子对象/链接属性上?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/31174295/