bugreport.ipynb

{
 "cells": [
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "normal-palace",
   "metadata": {},
   "outputs": [],
   "source": [
    "import contextvars, asyncio\n",
    "VAR = contextvars.ContextVar(\"VAR\", default=\"default\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "boxed-opportunity",
   "metadata": {},
   "outputs": [],
   "source": [
    "async def produce_result(x):\n",
    "    return x\n",
    "\n",
    "async def read_var():\n",
    "    print(\"Var:\", VAR.get())"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "lesbian-signature",
   "metadata": {},
   "source": [
    "## The following is broken"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "comic-gambling",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<Token var=<ContextVar name='VAR' default='default' at 0x7fb04c42e1d0> at 0x7fb04c498dc0>"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "result = await produce_result(\"bug fixed yayy\")\n",
    "VAR.set(result)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "minimal-milwaukee",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Var: default\n"
     ]
    }
   ],
   "source": [
    "await read_var()"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "arranged-monitoring",
   "metadata": {},
   "source": [
    "## The following works"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "upset-portugal",
   "metadata": {},
   "outputs": [],
   "source": [
    "result = await produce_result(\"this worked before\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "virtual-calendar",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "<Token var=<ContextVar name='VAR' default='default' at 0x7fb04c42e1d0> at 0x7fb04c4980c0>"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "VAR.set(result)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "collected-leave",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Var: this worked before\n"
     ]
    }
   ],
   "source": [
    "await read_var()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "regular-cursor",
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "6.2.0\n"
     ]
    }
   ],
   "source": [
    "import ipykernel\n",
    "print(ipykernel.__version__)"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Default (Python 3.8)",
   "language": "python",
   "name": "default_python3.8"
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  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.8.10"
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 "nbformat": 4,
 "nbformat_minor": 5
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