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 "cells": [
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Defining `otherwise` type\n",
    "\n",
    "In certain cases, it is required to be able to allow the \"else case\" when defining a particular attribute of a class. For instance, let us say our attribute should be a vector of size 3, but if it is not, a string should be allowed.\n",
    "\n",
    "A class with imposed typesystem would be:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "import ubermagutil.typesystem as ts\n",
    "\n",
    "\n",
    "@ts.typesystem(a=ts.Vector(size=3, otherwise=str))\n",
    "class DecoratedClass:\n",
    "    def __init__(self, a):\n",
    "        self.a = a"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Now, we can instantiate the class and pass the vector of length 3."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "(0, 1, 2)"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "dc = DecoratedClass(a=(0, 1, 2))\n",
    "dc.a"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Because we also defined `otheriwse` parameter, we can also assign a string."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "dc.a = \"Mihajlo Pupin\""
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "However if we pass an integer or a size 2 tuple, an exception is raised:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Exception raised.\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    dc.a = 23\n",
    "except TypeError:\n",
    "    print(\"Exception raised.\")"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Exception raised.\n"
     ]
    }
   ],
   "source": [
    "try:\n",
    "    dc.a = (1, 2)\n",
    "except ValueError:\n",
    "    print(\"Exception raised.\")"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "Attempts to assign a new value to the attribute, did not affect its value."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'Mihajlo Pupin'"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "dc.a"
   ]
  }
 ],
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