Magic Values ✨

magicvaluesv2.ipynb

{
 "cells": [
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   "cell_type": "code",
   "execution_count": 1,
   "id": "edc8c846-2741-4bc0-8e88-7115806ec913",
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "Version 1.0.5\n"
     ]
    }
   ],
   "source": [
    "%load_ext nb_mypy\n",
    "\n",
    "# Ignore no_redef https://github.com/python/mypy/issues/11065"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "2594d022-6287-432f-9168-f3a4bac89e40",
   "metadata": {},
   "outputs": [],
   "source": [
    "from typing import Optional, List, Type, Dict, Any\n",
    "\n",
    "class MetaConstant(type):\n",
    "    def __repr__(cls) -> str:\n",
    "        parent = cls.mro()[1]\n",
    "        if parent == object:\n",
    "            return cls.__name__\n",
    "        else:\n",
    "            repr = f\"{parent.__name__}.{cls.__name__}\"\n",
    "            if hasattr(cls, \"_value\"):\n",
    "                repr += f'(\\'{cls._value}\\')'\n",
    "            return repr\n",
    "\n",
    "\n",
    "class Constant(metaclass=MetaConstant):\n",
    "    _value: str\n",
    "    def __new__(\n",
    "        cls, val: Optional[str] = None, _visited: Optional[List[Type]] = None\n",
    "    ) -> \"Constant\":\n",
    "        if _visited is None:\n",
    "            _visited = []\n",
    "        _value: Optional[str] = getattr(cls, \"_value\", None)\n",
    "        if _value is None and val is None:\n",
    "            msg = f'Abstract {cls.__bases__[0].__name__} \"{cls.__name__}\" cannot be instantiated'\n",
    "            raise TypeError(msg)\n",
    "        elif _value is None:\n",
    "            # DFS through the class tree to find a matching subclass.\n",
    "            for child in cls.__subclasses__():\n",
    "                try:\n",
    "                    if match := child.__new__(child, val, _visited=_visited):\n",
    "                        return match\n",
    "                except:\n",
    "                    continue\n",
    "            # Compile a list of the subclassese we've tried for a better exception message.\n",
    "            valids = \", \".join([f\"{c}\" for c in _visited])\n",
    "            msg = f\"invalid {cls.__name__}:'{val}' is not valid for any {cls.__name__}s: [{valids}]\"\n",
    "            raise ValueError(msg)\n",
    "        elif val is None:\n",
    "            # Default case.\n",
    "            return super(Constant, cls).__new__(cls)\n",
    "        else:\n",
    "            # Base case for DFS.\n",
    "            if _value == val:\n",
    "                return super(Constant, cls).__new__(cls)\n",
    "            else:\n",
    "                _visited.append(cls)\n",
    "                msg = f\"invalid value for {cls}: '{val}'\"\n",
    "                raise ValueError(msg)\n",
    "\n",
    "    def __init_subclass__(cls) -> None:\n",
    "        \"\"\"Register subclass as parent attribute\n",
    "        Ex. Datacenter.fra4\n",
    "        \"\"\"\n",
    "        setattr(type(cls), cls.__name__, cls)\n",
    "\n",
    "    @property\n",
    "    def value(self) -> str:\n",
    "        return self._value\n",
    "\n",
    "    def __repr__(self) -> str:\n",
    "        return \"Value: \"+self._value\n",
    "\n",
    "    def __str__(self) -> str:\n",
    "        return self._value\n",
    "\n",
    "    def __eq__(self, other:Any) -> bool:\n",
    "        return self._value == other._value\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "ae4f3d1f-ee06-4e8d-b0ef-f9b2f14cb8b3",
   "metadata": {},
   "outputs": [],
   "source": [
    "class Location(Constant):\n",
    "    DataCenter: \"DataCenter\"\n",
    "    AvailabilityZone: \"AvailabilityZone\"\n",
    "\n",
    "class DataCenter(Location):\n",
    "    ams1: \"ams1\"\n",
    "    lon1: \"lon1\"\n",
    "\n",
    "class ams1(DataCenter):\n",
    "    _value = \"ams1\"\n",
    "\n",
    "class lon1(DataCenter):\n",
    "    _value = \"lon1\"\n",
    "\n",
    "class AvailabilityZone(Location):\n",
    "    west1_a: \"west1_a\"\n",
    "    west2_a: \"west2_a\"\n",
    "    \n",
    "class west1_a(AvailabilityZone):\n",
    "    _value = \"west1-a\"\n",
    "    \n",
    "class west2_a(AvailabilityZone):\n",
    "    _value = \"west2-a\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "0689f3c7-b6d5-4103-a522-bf9d717d3787",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "DataCenter.ams1('ams1')"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Typed\n",
    "ams1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "a61b74e4-e7d8-4412-b916-3adb20613b8a",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "Value: ams1"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Singleton value\n",
    "ams1()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "52a2d6d6-87e5-44cf-871e-22dae46fbc7d",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'ams1'"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "ams1().value"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "bf73bc28-77d0-4127-b29b-ba6595d1e741",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "ams1() == ams1()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "1d7ab03c-9cb0-48cf-8478-3b1de3fa3eb7",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "\"My datacenter is ams1=DataCenter.ams1('ams1')\""
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# REPR, string format works\n",
    "f\"My datacenter is {ams1=}\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "id": "20e44be6-5a02-44ae-9aac-32198018aa81",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'ams1'"
      ]
     },
     "execution_count": 9,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Validation\n",
    "DataCenter(\"ams1\").value"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "id": "e70ccf70-d3b6-418e-926a-96e59fe93b18",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'ams1'"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "Location(\"ams1\").value"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "id": "061b83a9-68d7-4f9c-a252-3a23a6842d37",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "DataCenter.ams1('ams1')"
      ]
     },
     "execution_count": 11,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "type(Location(\"ams1\"))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "id": "b0858aad-98b0-4413-97fc-835a0dbba4e6",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "AvailabilityZone.west1_a('west1-a')"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "type(Location(\"west1-a\"))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 13,
   "id": "31252ddf-da6f-4cbb-b49b-e7fd13d89011",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "invalid DataCenter:'foo1' is not valid for any DataCenters: [DataCenter.ams1('ams1'), DataCenter.lon1('lon1')]\n"
     ]
    }
   ],
   "source": [
    "# Free Validation with helpful error messages!\n",
    "try:\n",
    "    DataCenter(\"foo1\")\n",
    "except ValueError as e:\n",
    "    print(e)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 17,
   "id": "332ba91f-4718-4fac-9d86-4a19f2e86bd7",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "invalid Location:'foo1' is not valid for any Locations: [DataCenter.ams1('ams1'), DataCenter.lon1('lon1'), AvailabilityZone.west1_a('west1-a'), AvailabilityZone.west2_a('west2-a')]\n"
     ]
    }
   ],
   "source": [
    "# Free Validation with helpful error messages!\n",
    "try:\n",
    "    Location(\"foo1\")\n",
    "except ValueError as e:\n",
    "    print(e)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 14,
   "id": "c5244817-7bb1-46cc-a2e7-a2692125cfbc",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 14,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "# Multiple ways to instantiate, type stable output\n",
    "Location(\"ams1\") == DataCenter(\"ams1\") == Location.DataCenter.ams1 == DataCenter.ams1 == ams1()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 15,
   "id": "152b951a-ea0a-43c9-8830-17f04c8c17cb",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "True"
      ]
     },
     "execution_count": 15,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "type(Location(\"ams1\")) == type(DataCenter(\"ams1\")) == ams1"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 16,
   "id": "58c332d2-68bf-4b75-9308-04e5c57bc111",
   "metadata": {},
   "outputs": [],
   "source": [
    "def print_my_location(location:Location):\n",
    "    print(location)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 18,
   "id": "5b17faaf-5a07-4b13-a6b7-32697f82cb9d",
   "metadata": {},
   "outputs": [
    {
     "name": "stderr",
     "output_type": "stream",
     "text": [
      "<cell>2: \u001b[1m\u001b[31merror:\u001b[m Argument 1 to \u001b[m\u001b[1m\"print_my_location\"\u001b[m has incompatible type \u001b[m\u001b[1m\"str\"\u001b[m; expected \u001b[m\u001b[1m\"Location\"\u001b[m  \u001b[m\u001b[33m[arg-type]\u001b[m\n"
     ]
    }
   ],
   "source": [
    "def wrapper(value:str):\n",
    "    print_my_location(value)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "id": "38877ca9-e64c-4354-9911-651911955e5e",
   "metadata": {},
   "outputs": [],
   "source": [
    "from multimethod import multimethod\n",
    "\n",
    "DOMAIN = \"moll.dev\"\n",
    "\n",
    "@multimethod # type: ignore[no-redef]\n",
    "def generate_vm_name(vmname:str, location:Location):\n",
    "    raise ValueError(f\"Location '{type(location)}' not supported yet!\")\n",
    "\n",
    "@multimethod # type: ignore[no-redef]\n",
    "def generate_vm_name(vmname:str, location:DataCenter) -> str:\n",
    "    print(type(location))\n",
    "    return f\"{vmname}.{location}.{DOMAIN}\"    "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "id": "db8fd44f-bc75-4b99-8892-34dce44394c9",
   "metadata": {
    "jupyter": {
     "source_hidden": true
    }
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "DataCenter.ams1('ams1')\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "'test1-vm.ams1.moll.dev'"
      ]
     },
     "execution_count": 21,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "generate_vm_name(\"test1-vm\", Location(\"ams1\"))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "id": "4a6951ac-e7ae-42c0-b54a-093bd79cd40d",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Got exception >>> Location 'AvailabilityZone.west2_a('west2-a')' not supported yet!\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    generate_vm_name(\"test1-vm\", Location(\"west2-a\"))\n",
    "except ValueError as e:\n",
    "    print(f\"Got exception >>> {e}\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 24,
   "id": "a1f9d497-3513-4d5c-b01c-b173b564b5f6",
   "metadata": {},
   "outputs": [],
   "source": [
    "@multimethod\n",
    "def generate_vm_name(vmname:str, location:AvailabilityZone) -> str:\n",
    "    print(type(location))\n",
    "    return f\"{vmname}-{location}.{DOMAIN}\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 25,
   "id": "6845466c-9433-4d67-a3b0-688f837b80fd",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "AvailabilityZone.west2_a('west2-a')\n"
     ]
    },
    {
     "data": {
      "text/plain": [
       "'test1-vm-west2-a.moll.dev'"
      ]
     },
     "execution_count": 25,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "generate_vm_name(\"test1-vm\", Location(\"west2-a\"))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 26,
   "id": "79e3298c-9770-4e5b-b1e8-0f0625584627",
   "metadata": {},
   "outputs": [],
   "source": [
    "class Environment(Constant):\n",
    "    Prod:\"Prod\"\n",
    "    Dev:\"Dev\"\n",
    "    PCC:\"PCC\"\n",
    "    \n",
    "class Prod(Environment):\n",
    "    _value = \"prod\"\n",
    "\n",
    "class Dev(Environment):\n",
    "    _value = \"dev\"\n",
    "\n",
    "class PCC(Environment):\n",
    "    _value = \"pcc\""
   ]
  },
  {
   "cell_type": "markdown",
   "id": "26c8465a-1f7b-4d26-a09b-e8fa499681b7",
   "metadata": {},
   "source": [
    "| ↓env \\ location → | lon1 | ams1 | west1-a | west2-a |\n",
    "| ----------------- | ---- | ---- | ------- | ------- |\n",
    "| prod              | ✅    | ✅    | ✅       | ✅       |\n",
    "| dev               | ❌    | ❌    | ✅       | ✅       |\n",
    "| pcc               | ❌    | ✅    | ❌       | ❌       |"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 28,
   "id": "f1902d58-3284-4cf5-b24d-4d8378b1cd79",
   "metadata": {},
   "outputs": [],
   "source": [
    "@multimethod # type: ignore[no-redef]\n",
    "def check(environment:Environment, location:Location):\n",
    "    # log f\"Not a supported deployment combination ({environment}, {location})!\"\n",
    "    return False\n",
    "\n",
    "@multimethod # type: ignore[no-redef]\n",
    "def check(environment:Prod, location:Location):\n",
    "    return True\n",
    "\n",
    "@multimethod # type: ignore[no-redef]\n",
    "def check(environment:Dev, location:AvailabilityZone):\n",
    "    return True\n",
    "\n",
    "@multimethod # type: ignore[no-redef]\n",
    "def check(environment:Dev, location:AvailabilityZone):\n",
    "    return True\n",
    "\n",
    "@multimethod # type: ignore[no-redef]\n",
    "def check(environment:PCC, location:ams1):\n",
    "    return True"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 29,
   "id": "88f68c3f-44ce-467d-98b4-4d75133fda13",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "\tlon1\tams1\twest1-a\twest2-a\n",
      "prod\t✅\t✅\t✅\t✅\t\n",
      "dev\t❌\t❌\t✅\t✅\t\n",
      "pcc\t❌\t✅\t❌\t❌\t\n"
     ]
    }
   ],
   "source": [
    "environments = [Prod(), Dev(), PCC()]\n",
    "locations = [lon1(), ams1(), west1_a(), west2_a()]\n",
    "\n",
    "print(f\"\\t{'\\t'.join([str(l) for l in locations])}\")\n",
    "for environment in environments:\n",
    "    print(environment, end=\"\\t\")\n",
    "    for location in locations:\n",
    "        val = \"✅\" if check(environment, location) else \"❌\"\n",
    "        print(val, end=\"\\t\")\n",
    "    print()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "id": "08041963-2f50-460c-a1db-522dc8d5866a",
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    "collapsed": true,
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   "source": []
  }
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