I want to generate some classes, which automatically sets an existing one FieldDescriptor
by using the values from enum.
I want to generate the following classes without writing them:
GEN_STING
, GEN_BIGINT
, GEN_FLOAT
For some reason I always have problem with the:
__init__()
What is the proper solution for this?
from enum import Enum
from typing import Union, Type
from dataclasses import dataclass
import numpy as np
class FieldPairingTypes(Enum):
STRING = (str, "string", "keyword")
BIGINT = (np.int64, "bigint", "long")
FLOAT = (np.float64, "double", "double")
@dataclass
class FieldDescriptor:
original_field_name: str
datalake_field_name: str
datalake_field_type: Type
glue_field_type: str
datamart_field_type: Union[str, Type]
def __init__(self, ofn, dfn, field_type: FieldPairingTypes):
self.original_field_name = ofn
self.datalake_field_name = dfn
self.datalake_field_type, self.glue_field_type, self.datamart_field_type = field_type.value
def generate_class(class_name, field_type):
def __init__(self, ofn, dfn):
super().__init__(ofn, dfn, field_type)
attrs = {
# "__init__": __init__,
#"__init__": FieldDescriptor.__init__,
"__init__": lambda x, y: FieldDescriptor.__init__(x, y, field_type),
}
return type(class_name, (FieldDescriptor,), attrs)
generated_classes = {}
for value in FieldPairingTypes:
class_name = "GEN_" + str(value).split(".")[-1]
generated_classes[class_name] = generate_class(class_name, value)
for class_name, generated_class in generated_classes.items():
instance = generated_class("Hello", "World")
print(f"{class_name}: {instance.datalake_field_type}")
What is the proper solution for this?
The easiest fix you can make is to change:
"__init__": lambda x, y: FieldDescriptor.__init__(x, y, field_type),
To:
"__init__": lambda self, x, y: FieldDescriptor.__init__(self, x, y, field_type),
You were forgetting to provide your __init__
function with an self
argument and passing that to FieldDescriptor.__init__
.
If you want to use super
, you could, you just cannot use the zero-argument form. You would need something like:
def generate_class(class_name, field_type):
klass = type(class_name, (FieldDescriptor,), {})
def __init__(self, ofn, dfn):
super(klass, self).__init__(ofn, dfn, field_type)
klass.__init__ = __init__
return klass
so create the class first so you can reference it and make the super
call correctly.