Class vs. instance attributes

demo.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "* Inspired by https://stackoverflow.com/q/45284838/671013\n",
    "* We will have three passes over the code below; each time changing something small in the class' definition"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "class Foo:\n",
    "    name=\"some name\"\n",
    "    tricks=list()  # 1st step\n",
    "    def __init__(self, name):\n",
    "        self.name=name\n",
    "        # We will uncomment this shortly\n",
    "        self.tricks=[]  # 2nd step\n",
    "        self.tricks.append(name)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "f\"{id(Foo.tricks) = }\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "f1=Foo(\"hello world\")\n",
    "f\"{f1.name = }\", f\"{f1.tricks = }\", f\"{id(f1.tricks) = }\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "f2=Foo(\"bye world\")\n",
    "f\"{f2.name = }\", f\"{f2.tricks = }\", f\"{id(f2.tricks) = }\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "f\"{f1.name = }\", f\"{f1.tricks = }\""
   ]
  },
  {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {},
   "outputs": [],
   "source": [
    "f\"{id(Foo.tricks) = }\", f\"{id(f1.tricks) = }\", f\"{id(f2.tricks) = }\""
   ]
  }
 ],
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