fork download 
  1. from ctypes import *
  2. from abc import ABC, abstractmethod, ABCMeta
  3.  
  4.  
  5. class FinalMeta(ABCMeta, type(Structure)):
  6.     def __new__(mcs, name, bases, namespace, **kwargs):
  7.         print("FinalMeta.__new__(mcs, name, bases, namespace, **kwargs)")
  8.         print("  mcs =", mcs)
  9.         print("  name =", name)
  10.         print("  bases =", bases)
  11.         print("  namespace =", namespace)
  12.         print("  kwargs =", kwargs)
  13.         #Here you should call the type __new__ method
  14.         cls = type.__new__(mcs, name, bases, namespace, **kwargs)
  15.         print("<-- cls =", cls)
  16.         print()
  17.         return cls
  18.  
  19.  
  20.  
  21.  
  22. class MessageBase(ABC, Structure, metaclass=FinalMeta):
  23.     def __init__(self, *args, **kwargs):
  24.         super().__init__()
  25.  
  26.     @property
  27.     @abstractmethod
  28.     def format(self):
  29.         pass
  30.  
  31. class ConcreteMessage(MessageBase):
  32.     _fields_ = [("x", c_int)]
  33.     @property
  34.     def format(self):
  35.         return "dummy"
  36.  
  37. ConcreteMessage(1)
Runtime error #stdin #stdout #stderr 0.13s 24016KB
comments (?)
stdin 
Standard input is empty
stdout 
FinalMeta.__new__(mcs, name, bases, namespace, **kwargs)
  mcs = <class '__main__.FinalMeta'>
  name = MessageBase
  bases = (<class 'abc.ABC'>, <class '_ctypes.Structure'>)
  namespace = {'__module__': '__main__', '__qualname__': 'MessageBase', '__init__': <function MessageBase.__init__ at 0x2b4be2f9e9d8>, 'format': <property object at 0x2b4be2e81868>, '__classcell__': <cell at 0x2b4be2f7a1c8: empty>}
  kwargs = {}
<-- cls = <class '__main__.MessageBase'>

FinalMeta.__new__(mcs, name, bases, namespace, **kwargs)
  mcs = <class '__main__.FinalMeta'>
  name = ConcreteMessage
  bases = (<class '__main__.MessageBase'>,)
  namespace = {'__module__': '__main__', '__qualname__': 'ConcreteMessage', '_fields_': [('x', <class 'ctypes.c_int'>)], 'format': <property object at 0x2b4be2f83e08>}
  kwargs = {}
<-- cls = <class '__main__.ConcreteMessage'>
stderr 
Traceback (most recent call last):
  File "./prog.py", line 37, in <module>
TypeError: abstract class
https://ideone.com/87bTWU
language:
Python 3 (python  3.9.5)
created:
3 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!