A Python library that allows you to define abstract properties for dataclasses, bridging the gap between abstract base classes (ABCs) and dataclasses.
Install the library using pip:
pip install dataclassabcThe dataclassabc decorator enables the use of abstract properties within dataclasses.
It resolves abstract properties defined in an abstract base class (ABC) and enforces their implementation through fields in the derived dataclass.
Here's how you can define an abstract property in a base class and implement it in a derived dataclass:
from abc import ABC, abstractmethod
from dataclassabc import dataclassabc
# Define an abstract base class with an abstract property
class A(ABC):
@property
@abstractmethod
def name(self) -> str: ...
# Use the dataclassabc decorator to implement the abstract property in a dataclass
@dataclassabc(frozen=True)
class B(A):
# Implementing the abstract property 'name'
name: strUsing the standard dataclass decorator from the dataclasses module to implement abstract properties will result in a TypeError, as shown below:
from abc import ABC, abstractmethod
from dataclasses import dataclass
@dataclass(frozen=True)
class B(A):
name: str
# TypeError: Can't instantiate abstract class B without an implementation for abstract method 'name'
b = B(name='A')You can define mutable abstract properties by using the @property and @name.setter decorators in the abstract class. The following example demonstrates how to define and set a mutable property:
from abc import ABC, abstractmethod
from dataclassabc import dataclassabc
class A(ABC):
@property
@abstractmethod
def name(self) -> str: ...
@name.setter
@abstractmethod
def name(self, val: str): ...
@dataclassabc
class B(A):
name: str
b = B(name='A')
# modify the mutable variable
b.name = 'B'
# Output will be b=B(name='B')
print(f'{b=}')