abcmeta
Python meta class and abstract method library with restrictions.
This library provides a restricted way to validate abstract methods. The Python's default abstract method library only validates the methods that exist in the derived classes and nothing else. What this library provides is apart from that validation it provides validations over the method's signature. All you need is to import ABCMeta and abstractmethod from this library.
It works on both annotations and without annotations methods.
Installation
You can install the package by pip:
$ pip install abcmeta
Note: abcmeta supports Python3.6+.
Quick start
from typing import Dict, Text
from abcmeta import ABCMeta, abstractmethod
class Base(ABCMeta):
@abstractmethod
def method_2(self, name: Text, age: int) -> Dict[Text, Text]:
"""Abstract method."""
@abstractmethod
def method_3(self, name, age):
"""Abstract method."""
class Drived(Base):
def method_2(self, name: Text, age: int) -> Dict[Text, Text]:
return {"name": "test"}
def method_3(self, name, age):
pass
If you put a different signature, it will raise an error with 'diff' format with hints about what you've missed:
class Drived(Base):
def method_2(self, name: Text, age: int) -> List[Text]:
return {"name": "test"}
And it will raise:
Traceback (most recent call last):
File "/Workspaces/test.py", line 41, in <module>
class Drived(Base):
File "/usr/lib/python3.9/abc.py", line 85, in __new__
cls = super().__new__(mcls, name, bases, namespace, **kwargs)
File "/abcmeta/__init__.py", line 179, in __init_subclass__
raise AttributeError(
AttributeError: Signature of the derived method is not the same as parent class:
- method_2(self, name: str, age: int) -> Dict[str, str]
? ^ ^ -----
+ method_2(self, name: str, age: int) -> List[str]
? ^ ^
Derived method expected to return in 'typing.Dict[str, str]' type, but returns 'typing.List[str]'
For different parameter names:
class Drived(Base):
def method_2(self, username: Text, age: int) -> List[Text]:
return {"name": "test"}
And it will raise:
Traceback (most recent call last):
File "/Workspaces/test.py", line 41, in <module>
class Drived(Base):
File "/usr/lib/python3.9/abc.py", line 85, in __new__
cls = super().__new__(mcls, name, bases, namespace, **kwargs)
File "/abcmeta/__init__.py", line 180, in __init_subclass__
raise AttributeError(
AttributeError: Signature of the derived method is not the same as parent class:
- method_2(self, name: str, age: int) -> Dict[str, str]
+ method_2(self, username: str, age: int) -> Dict[str, str]
? ++++
Derived method expected to get name paramter, but gets username
