[英]Python dataclasses inheritance part of attributes from parent dataclass
I constructed multiple base dataclass
.我构建了多个基础
dataclass
。 Now I want to construct a child dataclass
inheriting from these base classes, but may inherit part of attributes defined in some base classes.现在我想构造一个继承自这些基类的子
dataclass
类,但可能会继承某些基类中定义的部分属性。 Examples can be:示例可以是:
import dataclasses
@dataclasses.dataclass
class A:
a: int = None
b: float = None
c: str = None
@dataclasses.dataclass
class B:
d: int = None
b: float = 3.5
@dataclasses.dataclass
class C:
e: int = None
f: float = 3.5
g: int = None
@dataclasses.dataclass
class D(A, B):
def __post_init__(self):
for _field, _field_property in C.__dataclass_fields__.items():
if _field != "g":
setattr(self, _field, _field_property.default)
Namely, I want to construct a child class D
inheriting A
and B
, and attributes in C
except g
.即,我想构造一个继承
A
和B
的子类D
,以及C
除g
之外的属性。 Checking the child class D
检查子类
D
>>> D.__dataclass_fields__.keys() # got dict_keys(['d', 'b', 'a', 'c'])
>>> d = D(a=4, b=2, c=5, d=3.4, e=2.1, g=55)
Traceback (most recent call last):
File "<pyshell#77>", line 1, in <module>
d = D(a=4, b=2, c=5, d=3.4, e=2.1, g=55)
TypeError: __init__() got an unexpected keyword argument 'e'
And和
>>> D.__dict__.keys()
dict_keys(['__module__', '__post_init__', '__doc__', '__dataclass_params__', '__dataclass_fields__', '__init__', '__repr__', '__eq__', '__hash__'])
When I changed __post_init__
to __init__
and using super().__init__()
for the inheritance, still can't the attributes from class C
and lose the advantage of dataclass
, ie,当我将
__post_init__
更改为__init__
并使用super().__init__()
进行继承时,仍然无法获取类C
的属性并失去dataclass
的优势,即,
>>> @dataclasses.dataclass
class D(A, B):
def __init__(self):
super().__init__()
for _field, _field_property in C.__dataclass_fields__.items():
if _field != "g":
setattr(self, _field, _field_property.default)
And run并运行
>>> d = D(a=4, b=2, c=5, d=3.4, e=2.1, g=55)
Traceback (most recent call last):
File "<pyshell#81>", line 1, in <module>
d = D(a=4, b=2, c=5, d=3.4, e=2.1, g=55)
TypeError: __init__() got an unexpected keyword argument 'a'
What should I do?我该怎么办?
Similar as what proposed by @GiacomoAlzetta, I suddenly come out that idea using dataclasses.make_dataclass
, ie, generate a copy of C
but excluding attribute g
, ie,如什么建议@GiacomoAlzetta类似,我突然用出来这个想法
dataclasses.make_dataclass
,即生成的副本C
但不包括属性g
,即
<<< C_part = dataclasses.make_dataclass("C_part", [(_field, _field_property.type, _field_property.default) for _field, _field_property in C.__dataclass_fields__.items() if _field != "g"])
Thus I have因此我有
>>> C_part.__dataclass_fields__.keys() # dict_keys(['e', 'f'])
Then the D
can be obtained by那么
D
可以通过
>>> @dataclasses.dataclass
class D(A, B, C_part):
pass
>>> d = D(a=4, b=2, c=5, d=3.4, e=2.1, f=55)
>>> d
D(e=2.1, f=55, d=3.4, b=2, a=4, c=5)
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