Override Checking

override_guard.ipynb

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     "text": [
      ".../site-packages/ipykernel/__main__.py:23: UserWarning: method 'double' on class 'B' implicitly overrides 'A'\n"
     ]
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   "source": [
    "import warnings\n",
    "\n",
    "OVERRIDE_FLAG = '_explicit_override'\n",
    "\n",
    "def overrides(method):\n",
    "    setattr(method, OVERRIDE_FLAG, True)\n",
    "    return method\n",
    "\n",
    "class OverrideGuard(type):\n",
    "    def __init__(cls, clsname, bases, methods):\n",
    "        super().__init__(clsname, bases, methods)\n",
    "        for method_name, method in methods.items():\n",
    "            if method_name.startswith('_'):\n",
    "                continue\n",
    "            \n",
    "            first = None\n",
    "            for mro_cls in reversed(cls.__mro__):\n",
    "                if method_name in mro_cls.__dict__:\n",
    "                    if not first:\n",
    "                        first = mro_cls\n",
    "                    else:\n",
    "                        if not getattr(mro_cls.__dict__[method_name], OVERRIDE_FLAG, False):\n",
    "                            warnings.warn(f\"method '{method_name}' \"\n",
    "                                          f\"on class '{mro_cls.__name__}' \"\n",
    "                                          f\"implicitly overrides '{first.__name__}'\")\n",
    "\n",
    "class A(metaclass=OverrideGuard):\n",
    "    def double(self, x):\n",
    "        return 2*x\n",
    "    \n",
    "class B(A):\n",
    "    def double(self, x):\n",
    "        return 4*x\n",
    "    \n",
    "class C(A):\n",
    "    @overrides\n",
    "    def double(self, x):\n",
    "        return 4*x"
   ]
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   "outputs": [
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     "text": [
      "100 loops, best of 3: 3 ms per loop\n"
     ]
    }
   ],
   "source": [
    "%%timeit -p1 test = A()\n",
    "sum(test.double(x) for x in range(10000))"
   ]
  },
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   "cell_type": "code",
   "execution_count": 3,
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     "text": [
      "100 loops, best of 3: 3 ms per loop\n"
     ]
    }
   ],
   "source": [
    "%%timeit -p1 test = B()\n",
    "sum(test.double(x) for x in range(10000))"
   ]
  },
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   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
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   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "100 loops, best of 3: 3 ms per loop\n"
     ]
    }
   ],
   "source": [
    "%%timeit -p1 test = C()\n",
    "sum(test.double(x) for x in range(10000))"
   ]
  },
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   "execution_count": null,
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