Hack to make Python look like C++

python-c.gif

PythonCpp.ipynb

{
 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Making Python Look Like C++\n",
    "\n",
    "This should never be used."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "default = object()\n",
    "\n",
    "class Cout(object):\n",
    "    def __init__(self, s=''):\n",
    "        self.s = str(s)\n",
    "    def __lshift__(self, s):\n",
    "        return Cout(self.s + str(s))\n",
    "    def __repr__(self):\n",
    "        print(self.s, end='')\n",
    "        return ''\n",
    "cout = Cout()\n",
    "endl = '\\n'\n",
    "            \n",
    "class Case(object):\n",
    "    def __call__(self, x):\n",
    "        return x\n",
    "case = Case()\n",
    "\n",
    "class Switch(object):\n",
    "    def __call__(self, obj):\n",
    "        self.obj = obj\n",
    "        return self\n",
    "    def __or__(self, items):\n",
    "        output = items.get(self.obj, items[default])\n",
    "        if isinstance(output, Cout):\n",
    "            print(output.s)\n",
    "        else:\n",
    "            return output\n",
    "switch = Switch()"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Python 3.5.1\n"
     ]
    }
   ],
   "source": [
    "import sys; print(\"Python\", sys.version[:5])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "hello world\n"
     ]
    },
    {
     "data": {
      "text/plain": []
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "cout << \"hello world\" << endl"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "about sqrt(2), as much as it matters\n"
     ]
    }
   ],
   "source": [
    "x = 1\n",
    "\n",
    "switch (x) | {\n",
    "    case (1):\n",
    "        cout << \"about sqrt(2), as much as it matters\",\n",
    "    case (2):\n",
    "        cout << \"about e, more or less\",\n",
    "    case (3):\n",
    "        cout << \"about pi, to a good approximation\",\n",
    "    default:\n",
    "        cout << \"I don't know what you're talking about\",\n",
    "}"
   ]
  }
 ],
 "metadata": {
  "kernelspec": {
   "display_name": "Python 3.5",
   "language": "",
   "name": "python3.5"
  },
  "language_info": {
   "codemirror_mode": {
    "name": "ipython",
    "version": 3
   },
   "file_extension": ".py",
   "mimetype": "text/x-python",
   "name": "python",
   "nbconvert_exporter": "python",
   "pygments_lexer": "ipython3",
   "version": "3.5.1"
  }
 },
 "nbformat": 4,
 "nbformat_minor": 0
}

This is fun :-)

Shorter version, by reusing the dict instead of using lists:

default = object()

class Cout(object):
    def __lshift__(self, obj):
        return obj
cout = Cout()

def case(x):
    return x

class Switch(object):
    def __call__(self, obj):
        self.obj = obj
        return self
    def __or__(self, D):
        output = D.get(self.obj, default)
        if output == default:
            try:
                output = D[default]
            except KeyError:
                raise RuntimeError("Missing default value")
        print(output)
switch = Switch()

Thanks @JanSchultz! I ended up changing it to a slightly different approach

This begs for StreamIO/BytesIO.

you should make it assert dominance