Use a metaclass to self-register subclasses to easily instatiate new objects and use an abstract base class

dynamics_metaclass.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "from abc import abstractmethod, ABCMeta"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 19,
   "metadata": {},
   "outputs": [],
   "source": [
    "class DynamicsMeta(ABCMeta):\n",
    "    def __init__(cls, name, bases, dct):\n",
    "        if not hasattr(cls, 'registry'):\n",
    "            cls.registry = {}\n",
    "        else:\n",
    "            dyn_id = name.lower()\n",
    "            cls.registry[dyn_id] = cls\n",
    "        super(DynamicsMeta, cls).__init__(name, bases, dct)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 20,
   "metadata": {},
   "outputs": [],
   "source": [
    "class Dynamics(metaclass=DynamicsMeta):\n",
    "    \n",
    "    @abstractmethod\n",
    "    def density_matrix(self):\n",
    "        pass\n",
    "    \n",
    "    @abstractmethod\n",
    "    def time_step(self):\n",
    "        pass\n",
    "    \n",
    "    @classmethod\n",
    "    def make_new(self, kind, *args, **kwargs):\n",
    "        return self.registry[kind](*args, **kwargs)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 21,
   "metadata": {},
   "outputs": [],
   "source": [
    "class PLDM(Dynamics):\n",
    "    def __init__(self, *args, **kwargs):\n",
    "        self.args = args\n",
    "        self.kwargs = kwargs\n",
    "    \n",
    "    def density_matrix(self):\n",
    "        return 'PLDM density matrix'\n",
    "    \n",
    "    def time_step(self):\n",
    "        return 'Advanced PLDM time'\n",
    "\n",
    "class IPLDM(Dynamics):\n",
    "    def __init__(self, *args, **kwargs):\n",
    "        self.args = args\n",
    "        self.kwargs = kwargs\n",
    "    \n",
    "    def density_matrix(self):\n",
    "        return 'IPLDM density matrix'\n",
    "    \n",
    "    def time_step(self):\n",
    "        return 'Advanced IPLDM time'\n",
    "\n",
    "class Broken(Dynamics):\n",
    "    def __init__(self, *args, **kwargs):\n",
    "        self.args = args\n",
    "        self.kwargs = kwargs\n",
    "    \n",
    "    def density_matrix(self):\n",
    "        return 'Broken density matrix'\n",
    "    "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 22,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "PLDM density matrix\n"
     ]
    }
   ],
   "source": [
    "pldm = Dynamics.make_new('pldm')\n",
    "print(pldm.density_matrix())"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 23,
   "metadata": {},
   "outputs": [
    {
     "ename": "TypeError",
     "evalue": "Can't instantiate abstract class Broken with abstract methods time_step",
     "output_type": "error",
     "traceback": [
      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m                                 Traceback (most recent call last)",
      "\u001b[0;32m<ipython-input-23-13055d4f9720>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mbroke\u001b[0m \u001b[0;34m=\u001b[0m \u001b[0mDynamics\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mmake_new\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m'broken'\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;32m<ipython-input-20-942ed3c02c9c>\u001b[0m in \u001b[0;36mmake_new\u001b[0;34m(self, kind, *args, **kwargs)\u001b[0m\n\u001b[1;32m     11\u001b[0m     \u001b[0;34m@\u001b[0m\u001b[0mclassmethod\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[1;32m     12\u001b[0m     \u001b[0;32mdef\u001b[0m \u001b[0mmake_new\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0mself\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0mkind\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m*\u001b[0m\u001b[0margs\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m**\u001b[0m\u001b[0mkwargs\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m:\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0;32m---> 13\u001b[0;31m         \u001b[0;32mreturn\u001b[0m \u001b[0mself\u001b[0m\u001b[0;34m.\u001b[0m\u001b[0mregistry\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0mkind\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m(\u001b[0m\u001b[0;34m*\u001b[0m\u001b[0margs\u001b[0m\u001b[0;34m,\u001b[0m \u001b[0;34m**\u001b[0m\u001b[0mkwargs\u001b[0m\u001b[0;34m)\u001b[0m\u001b[0;34m\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
      "\u001b[0;31mTypeError\u001b[0m: Can't instantiate abstract class Broken with abstract methods time_step"
     ]
    }
   ],
   "source": [
    "broke = Dynamics.make_new('broken')"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": []
  }
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