From b60ddeb64417a9e17c27140b274b76ee24d95aaf Mon Sep 17 00:00:00 2001
From: Anna Meyer <annapmeyer95@gmail.com>
Date: Fri, 21 Jul 2023 11:29:56 -0500
Subject: [PATCH] lec 15 notes
---
.../lec_14_comprehensions_notes.ipynb | 52 +-
.../lec_15_error_handling_notes.ipynb | 1093 +++++++++++++++++
2 files changed, 1135 insertions(+), 10 deletions(-)
create mode 100644 sum23/lecture_materials/15_Errors/lec_15_error_handling_notes.ipynb
diff --git a/sum23/lecture_materials/14_Comprehensions/lec_14_comprehensions_notes.ipynb b/sum23/lecture_materials/14_Comprehensions/lec_14_comprehensions_notes.ipynb
index 1c61d62..b4dd87d 100644
--- a/sum23/lecture_materials/14_Comprehensions/lec_14_comprehensions_notes.ipynb
+++ b/sum23/lecture_materials/14_Comprehensions/lec_14_comprehensions_notes.ipynb
@@ -734,6 +734,9 @@
"\n",
"for tuple_item in scores_dict.items():\n",
" print(tuple_item)\n",
+ " key = tuple_item[0]\n",
+ " val = tuple_item[1]\n",
+ " print(key,val)\n",
" \n",
"print(\"--------------------\")\n",
"\n",
@@ -796,14 +799,23 @@
},
{
"cell_type": "code",
- "execution_count": null,
+ "execution_count": 1,
"metadata": {},
- "outputs": [],
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Original: {'Nov': 28, 'Dec': 20, 'Jan': 10, 'Feb': 14}\n",
+ "New dict: {'Nov': -2.2222222222222223, 'Dec': -6.666666666666667, 'Jan': -12.222222222222223, 'Feb': -10.0}\n"
+ ]
+ }
+ ],
"source": [
"madison_fahrenheit = {'Nov': 28,'Dec': 20, 'Jan': 10,'Feb': 14}\n",
"print(\"Original:\", madison_fahrenheit)\n",
"\n",
- "madison_celsius = {key: ??? \\\n",
+ "madison_celsius = {key: 5 / 9 * (val - 32) \\\n",
" for key, val in madison_fahrenheit.items()}\n",
"print(\"New dict:\", madison_celsius)"
]
@@ -817,14 +829,23 @@
},
{
"cell_type": "code",
- "execution_count": null,
+ "execution_count": 2,
"metadata": {},
- "outputs": [],
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Original: {'Bob': '32', 'Cindy': '45', 'Alice': '39', 'Unknown': 'None'}\n",
+ "New dict: {'Bob': 32, 'Cindy': 45, 'Alice': 39, 'Unknown': None}\n"
+ ]
+ }
+ ],
"source": [
"scores_dict = {\"Bob\": \"32\", \"Cindy\" : \"45\", \"Alice\": \"39\", \"Unknown\": \"None\"}\n",
"print(\"Original:\", scores_dict)\n",
"\n",
- "updated_scores_dict = {???}\n",
+ "# updated_scores_dict = {???}\n",
" \n",
"# # step 1: add for statement\n",
"# updated_scores_dict = { ??? for key, val in scores_dict.items() ???}\n",
@@ -833,8 +854,8 @@
"# updated_scores_dict = { ??? if val.isdigit() else ??? for key, val in scores_dict.items()}\n",
"\n",
"# # step 3: fill in \"if\" and \"else\" values\n",
- "# updated_scores_dict = {key: int(val) if val.isdigit() else None \\\n",
- "# for key, val in scores_dict.items()}\n",
+ "updated_scores_dict = {key: int(val) if val.isdigit() else None \\\n",
+ " for key, val in scores_dict.items()}\n",
"\n",
"print(\"New dict:\", updated_scores_dict)"
]
@@ -848,9 +869,20 @@
},
{
"cell_type": "code",
- "execution_count": null,
+ "execution_count": 3,
"metadata": {},
- "outputs": [],
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "{'Bob': 83, 'Cindy': 87, 'Alice': 90, 'Meena': 93}"
+ ]
+ },
+ "execution_count": 3,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
"source": [
"scores_dict = {\"Bob\": [18, 72, 61, 5, 83], \n",
" \"Cindy\" : [27, 11, 55, 73, 87], \n",
diff --git a/sum23/lecture_materials/15_Errors/lec_15_error_handling_notes.ipynb b/sum23/lecture_materials/15_Errors/lec_15_error_handling_notes.ipynb
new file mode 100644
index 0000000..7713f92
--- /dev/null
+++ b/sum23/lecture_materials/15_Errors/lec_15_error_handling_notes.ipynb
@@ -0,0 +1,1093 @@
+{
+ "cells": [
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "# Error handling"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 1,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "# import statements\n",
+ "import math"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Warmup\n",
+ "\n",
+ "### Warmup 1: How does this recursion work? Try it in Python tutor"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "def chop(s):\n",
+ " if len(s) < 3:\n",
+ " return s[0]\n",
+ " else:\n",
+ " return s[1] + chop(s[2:])\n",
+ "\n",
+ "chop(\"abcdefghijklmnop\")"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "# Now, by hand, figure out this output\n",
+ "chop(\"987654\")"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Lecture 25: Error Handling\n",
+ "\n",
+ "**Learing Objectives:**\n",
+ " \n",
+ "- Explain the purpose of assert statements, try/except blocks, and raise statements.\n",
+ "\n",
+ "- Use an assert statement to force a program to crash, and trace code that uses assert.\n",
+ "\n",
+ "- Use try/except blocks to catch runtime errors and deal with them\n",
+ " - by specifying the exception(s) caught\n",
+ " - by using the exception object\n",
+ "\n",
+ "- Use the raise statement to raise an exception that may be caught in another part of the program\n",
+ "\n",
+ "- Hand trace code that uses assert, try/except blocks and raise statements\n",
+ "\n"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Why might you want your code to crash more?\n",
+ "\n",
+ "- It is easier to debug the program if we get a stack trace\n",
+ "- Semantic errors are the scariest because we don't get any kind of error\n",
+ "\n",
+ "### When is it fine for your code to crash less?\n",
+ "\n",
+ "- When user enters incorrect input, we simply want to display an error message and not crash\n",
+ "- When the program has syntax error, we definitely want the program to crash\n",
+ "\n",
+ "<div>\n",
+ "<img src=\"attachment:Theme.png\" width=\"600\"/>\n",
+ "</div>"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## Pizza Analyzer"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 2,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "def pizza_size(radius):\n",
+ " return (radius ** 2) * math.pi\n",
+ "\n",
+ "def slice_size(radius, slice_count):\n",
+ " total_size = pizza_size(radius)\n",
+ " return total_size * (1 / slice_count)\n",
+ "\n",
+ "def main():\n",
+ " for i in range(3):\n",
+ " # grab input\n",
+ " args = input(\"Enter pizza diameter(inches), slice count: \")\n",
+ " args = args.split(',')\n",
+ " radius = float(args[0].strip()) / 2\n",
+ " slices = int(args[1].strip())\n",
+ "\n",
+ " # pizza analysis\n",
+ " size = slice_size(radius, slices)\n",
+ " print('PIZZA: radius = {}, slices = {}, slice square inches = {}'\n",
+ " .format(radius, slices, size))"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Try valid input of 4, 4 for main invocation"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 3,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Enter pizza diameter(inches), slice count: 4,4\n",
+ "PIZZA: radius = 2.0, slices = 4, slice square inches = 3.141592653589793\n",
+ "Enter pizza diameter(inches), slice count: 10,0\n"
+ ]
+ },
+ {
+ "ename": "ZeroDivisionError",
+ "evalue": "division by zero",
+ "output_type": "error",
+ "traceback": [
+ "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+ "\u001b[0;31mZeroDivisionError\u001b[0m Traceback (most recent call last)",
+ "Cell \u001b[0;32mIn[3], line 1\u001b[0m\n\u001b[0;32m----> 1\u001b[0m \u001b[43mmain\u001b[49m\u001b[43m(\u001b[49m\u001b[43m)\u001b[49m\n",
+ "Cell \u001b[0;32mIn[2], line 17\u001b[0m, in \u001b[0;36mmain\u001b[0;34m()\u001b[0m\n\u001b[1;32m 14\u001b[0m slices \u001b[38;5;241m=\u001b[39m \u001b[38;5;28mint\u001b[39m(args[\u001b[38;5;241m1\u001b[39m]\u001b[38;5;241m.\u001b[39mstrip())\n\u001b[1;32m 16\u001b[0m \u001b[38;5;66;03m# pizza analysis\u001b[39;00m\n\u001b[0;32m---> 17\u001b[0m size \u001b[38;5;241m=\u001b[39m \u001b[43mslice_size\u001b[49m\u001b[43m(\u001b[49m\u001b[43mradius\u001b[49m\u001b[43m,\u001b[49m\u001b[43m \u001b[49m\u001b[43mslices\u001b[49m\u001b[43m)\u001b[49m\n\u001b[1;32m 18\u001b[0m \u001b[38;5;28mprint\u001b[39m(\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mPIZZA: radius = \u001b[39m\u001b[38;5;132;01m{}\u001b[39;00m\u001b[38;5;124m, slices = \u001b[39m\u001b[38;5;132;01m{}\u001b[39;00m\u001b[38;5;124m, slice square inches = \u001b[39m\u001b[38;5;132;01m{}\u001b[39;00m\u001b[38;5;124m'\u001b[39m\n\u001b[1;32m 19\u001b[0m \u001b[38;5;241m.\u001b[39mformat(radius, slices, size))\n",
+ "Cell \u001b[0;32mIn[2], line 6\u001b[0m, in \u001b[0;36mslice_size\u001b[0;34m(radius, slice_count)\u001b[0m\n\u001b[1;32m 4\u001b[0m \u001b[38;5;28;01mdef\u001b[39;00m \u001b[38;5;21mslice_size\u001b[39m(radius, slice_count):\n\u001b[1;32m 5\u001b[0m total_size \u001b[38;5;241m=\u001b[39m pizza_size(radius)\n\u001b[0;32m----> 6\u001b[0m \u001b[38;5;28;01mreturn\u001b[39;00m total_size \u001b[38;5;241m*\u001b[39m (\u001b[38;5;241;43m1\u001b[39;49m\u001b[43m \u001b[49m\u001b[38;5;241;43m/\u001b[39;49m\u001b[43m \u001b[49m\u001b[43mslice_count\u001b[49m)\n",
+ "\u001b[0;31mZeroDivisionError\u001b[0m: division by zero"
+ ]
+ }
+ ],
+ "source": [
+ "main()"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Can you think of any inputs that will make this program crash?\n",
+ "\n",
+ "Try each of these bad inputs:\n",
+ "- 10, 0: ZeroDivisionError\n",
+ "- 10: IndexError\n",
+ "- 10, hello: ValueError\n",
+ "- 10, 4.5: ValueError\n",
+ "- 10, -4: Semantic error\n",
+ "- -10, 4: Semantic error (scariest error for this example)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 4,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Enter pizza diameter(inches), slice count: 10, hi!\n"
+ ]
+ },
+ {
+ "ename": "ValueError",
+ "evalue": "invalid literal for int() with base 10: 'hi!'",
+ "output_type": "error",
+ "traceback": [
+ "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+ "\u001b[0;31mValueError\u001b[0m Traceback (most recent call last)",
+ "Cell \u001b[0;32mIn[4], line 1\u001b[0m\n\u001b[0;32m----> 1\u001b[0m \u001b[43mmain\u001b[49m\u001b[43m(\u001b[49m\u001b[43m)\u001b[49m\n",
+ "Cell \u001b[0;32mIn[2], line 14\u001b[0m, in \u001b[0;36mmain\u001b[0;34m()\u001b[0m\n\u001b[1;32m 12\u001b[0m args \u001b[38;5;241m=\u001b[39m args\u001b[38;5;241m.\u001b[39msplit(\u001b[38;5;124m'\u001b[39m\u001b[38;5;124m,\u001b[39m\u001b[38;5;124m'\u001b[39m)\n\u001b[1;32m 13\u001b[0m radius \u001b[38;5;241m=\u001b[39m \u001b[38;5;28mfloat\u001b[39m(args[\u001b[38;5;241m0\u001b[39m]\u001b[38;5;241m.\u001b[39mstrip()) \u001b[38;5;241m/\u001b[39m \u001b[38;5;241m2\u001b[39m\n\u001b[0;32m---> 14\u001b[0m slices \u001b[38;5;241m=\u001b[39m \u001b[38;5;28;43mint\u001b[39;49m\u001b[43m(\u001b[49m\u001b[43margs\u001b[49m\u001b[43m[\u001b[49m\u001b[38;5;241;43m1\u001b[39;49m\u001b[43m]\u001b[49m\u001b[38;5;241;43m.\u001b[39;49m\u001b[43mstrip\u001b[49m\u001b[43m(\u001b[49m\u001b[43m)\u001b[49m\u001b[43m)\u001b[49m\n\u001b[1;32m 16\u001b[0m \u001b[38;5;66;03m# pizza analysis\u001b[39;00m\n\u001b[1;32m 17\u001b[0m size \u001b[38;5;241m=\u001b[39m slice_size(radius, slices)\n",
+ "\u001b[0;31mValueError\u001b[0m: invalid literal for int() with base 10: 'hi!'"
+ ]
+ }
+ ],
+ "source": [
+ "main()\n"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 6,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Enter pizza diameter(inches), slice count: -10, 4\n",
+ "PIZZA: radius = -5.0, slices = 4, slice square inches = 19.634954084936208\n"
+ ]
+ },
+ {
+ "ename": "KeyboardInterrupt",
+ "evalue": "Interrupted by user",
+ "output_type": "error",
+ "traceback": [
+ "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+ "\u001b[0;31mKeyboardInterrupt\u001b[0m Traceback (most recent call last)",
+ "Cell \u001b[0;32mIn[6], line 1\u001b[0m\n\u001b[0;32m----> 1\u001b[0m \u001b[43mmain\u001b[49m\u001b[43m(\u001b[49m\u001b[43m)\u001b[49m\n",
+ "Cell \u001b[0;32mIn[2], line 11\u001b[0m, in \u001b[0;36mmain\u001b[0;34m()\u001b[0m\n\u001b[1;32m 8\u001b[0m \u001b[38;5;28;01mdef\u001b[39;00m \u001b[38;5;21mmain\u001b[39m():\n\u001b[1;32m 9\u001b[0m \u001b[38;5;28;01mfor\u001b[39;00m i \u001b[38;5;129;01min\u001b[39;00m \u001b[38;5;28mrange\u001b[39m(\u001b[38;5;241m3\u001b[39m):\n\u001b[1;32m 10\u001b[0m \u001b[38;5;66;03m# grab input\u001b[39;00m\n\u001b[0;32m---> 11\u001b[0m args \u001b[38;5;241m=\u001b[39m \u001b[38;5;28;43minput\u001b[39;49m\u001b[43m(\u001b[49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[38;5;124;43mEnter pizza diameter(inches), slice count: \u001b[39;49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[43m)\u001b[49m\n\u001b[1;32m 12\u001b[0m args \u001b[38;5;241m=\u001b[39m args\u001b[38;5;241m.\u001b[39msplit(\u001b[38;5;124m'\u001b[39m\u001b[38;5;124m,\u001b[39m\u001b[38;5;124m'\u001b[39m)\n\u001b[1;32m 13\u001b[0m radius \u001b[38;5;241m=\u001b[39m \u001b[38;5;28mfloat\u001b[39m(args[\u001b[38;5;241m0\u001b[39m]\u001b[38;5;241m.\u001b[39mstrip()) \u001b[38;5;241m/\u001b[39m \u001b[38;5;241m2\u001b[39m\n",
+ "File \u001b[0;32m~/miniforge3/lib/python3.10/site-packages/ipykernel/kernelbase.py:1191\u001b[0m, in \u001b[0;36mKernel.raw_input\u001b[0;34m(self, prompt)\u001b[0m\n\u001b[1;32m 1189\u001b[0m msg \u001b[38;5;241m=\u001b[39m \u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mraw_input was called, but this frontend does not support input requests.\u001b[39m\u001b[38;5;124m\"\u001b[39m\n\u001b[1;32m 1190\u001b[0m \u001b[38;5;28;01mraise\u001b[39;00m StdinNotImplementedError(msg)\n\u001b[0;32m-> 1191\u001b[0m \u001b[38;5;28;01mreturn\u001b[39;00m \u001b[38;5;28;43mself\u001b[39;49m\u001b[38;5;241;43m.\u001b[39;49m\u001b[43m_input_request\u001b[49m\u001b[43m(\u001b[49m\n\u001b[1;32m 1192\u001b[0m \u001b[43m \u001b[49m\u001b[38;5;28;43mstr\u001b[39;49m\u001b[43m(\u001b[49m\u001b[43mprompt\u001b[49m\u001b[43m)\u001b[49m\u001b[43m,\u001b[49m\n\u001b[1;32m 1193\u001b[0m \u001b[43m \u001b[49m\u001b[38;5;28;43mself\u001b[39;49m\u001b[38;5;241;43m.\u001b[39;49m\u001b[43m_parent_ident\u001b[49m\u001b[43m[\u001b[49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[38;5;124;43mshell\u001b[39;49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[43m]\u001b[49m\u001b[43m,\u001b[49m\n\u001b[1;32m 1194\u001b[0m \u001b[43m \u001b[49m\u001b[38;5;28;43mself\u001b[39;49m\u001b[38;5;241;43m.\u001b[39;49m\u001b[43mget_parent\u001b[49m\u001b[43m(\u001b[49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[38;5;124;43mshell\u001b[39;49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[43m)\u001b[49m\u001b[43m,\u001b[49m\n\u001b[1;32m 1195\u001b[0m \u001b[43m \u001b[49m\u001b[43mpassword\u001b[49m\u001b[38;5;241;43m=\u001b[39;49m\u001b[38;5;28;43;01mFalse\u001b[39;49;00m\u001b[43m,\u001b[49m\n\u001b[1;32m 1196\u001b[0m \u001b[43m\u001b[49m\u001b[43m)\u001b[49m\n",
+ "File \u001b[0;32m~/miniforge3/lib/python3.10/site-packages/ipykernel/kernelbase.py:1234\u001b[0m, in \u001b[0;36mKernel._input_request\u001b[0;34m(self, prompt, ident, parent, password)\u001b[0m\n\u001b[1;32m 1231\u001b[0m \u001b[38;5;28;01mexcept\u001b[39;00m \u001b[38;5;167;01mKeyboardInterrupt\u001b[39;00m:\n\u001b[1;32m 1232\u001b[0m \u001b[38;5;66;03m# re-raise KeyboardInterrupt, to truncate traceback\u001b[39;00m\n\u001b[1;32m 1233\u001b[0m msg \u001b[38;5;241m=\u001b[39m \u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mInterrupted by user\u001b[39m\u001b[38;5;124m\"\u001b[39m\n\u001b[0;32m-> 1234\u001b[0m \u001b[38;5;28;01mraise\u001b[39;00m \u001b[38;5;167;01mKeyboardInterrupt\u001b[39;00m(msg) \u001b[38;5;28;01mfrom\u001b[39;00m \u001b[38;5;28;01mNone\u001b[39;00m\n\u001b[1;32m 1235\u001b[0m \u001b[38;5;28;01mexcept\u001b[39;00m \u001b[38;5;167;01mException\u001b[39;00m:\n\u001b[1;32m 1236\u001b[0m \u001b[38;5;28mself\u001b[39m\u001b[38;5;241m.\u001b[39mlog\u001b[38;5;241m.\u001b[39mwarning(\u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mInvalid Message:\u001b[39m\u001b[38;5;124m\"\u001b[39m, exc_info\u001b[38;5;241m=\u001b[39m\u001b[38;5;28;01mTrue\u001b[39;00m)\n",
+ "\u001b[0;31mKeyboardInterrupt\u001b[0m: Interrupted by user"
+ ]
+ }
+ ],
+ "source": [
+ "main()"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### What was the scariest error in the above examples?"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "# - -10, 4: Semantic error (scariest error for this example)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## `assert` statements\n",
+ "- `assert` statements enable you to convert semantic errors into runtime errors\n",
+ " - runtime errors are easier to debug than semantic errors\n",
+ "- `assert` statements make your program very slow!\n",
+ " - so sometimes programmers disable these (we won't be learning about this)\n",
+ "- Syntax: `assert BOOLEAN_EXPRESSION`\n",
+ " - BOOLEAN_EXPRESSION evaluates to `True`: nothing happens (move on to next line of code)\n",
+ " - BOOLEAN_EXPRESSION evaluates to `False`: program carshes with `AssertionError`\n",
+ " \n",
+ "<div>\n",
+ "<img src=\"attachment:Assert.png\" width=\"450\"/>\n",
+ "</div>"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 8,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Enter your age: -5\n"
+ ]
+ },
+ {
+ "ename": "AssertionError",
+ "evalue": "",
+ "output_type": "error",
+ "traceback": [
+ "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+ "\u001b[0;31mAssertionError\u001b[0m Traceback (most recent call last)",
+ "Cell \u001b[0;32mIn[8], line 4\u001b[0m\n\u001b[1;32m 1\u001b[0m \u001b[38;5;66;03m# simple example\u001b[39;00m\n\u001b[1;32m 3\u001b[0m age \u001b[38;5;241m=\u001b[39m \u001b[38;5;28mint\u001b[39m(\u001b[38;5;28minput\u001b[39m(\u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mEnter your age: \u001b[39m\u001b[38;5;124m\"\u001b[39m))\n\u001b[0;32m----> 4\u001b[0m \u001b[38;5;28;01massert\u001b[39;00m age \u001b[38;5;241m>\u001b[39m\u001b[38;5;241m=\u001b[39m \u001b[38;5;241m0\u001b[39m \u001b[38;5;66;03m# if True, do nothing else, crash\u001b[39;00m\n\u001b[1;32m 5\u001b[0m \u001b[38;5;28mprint\u001b[39m(\u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mIn five years you will be\u001b[39m\u001b[38;5;124m\"\u001b[39m, age \u001b[38;5;241m+\u001b[39m \u001b[38;5;241m5\u001b[39m, \u001b[38;5;124m\"\u001b[39m\u001b[38;5;124myears old\u001b[39m\u001b[38;5;124m\"\u001b[39m)\n",
+ "\u001b[0;31mAssertionError\u001b[0m: "
+ ]
+ }
+ ],
+ "source": [
+ "# simple example\n",
+ "\n",
+ "age = int(input(\"Enter your age: \"))\n",
+ "assert age >= 0 # if True, do nothing else, crash\n",
+ "print(\"In five years you will be\", age + 5, \"years old\")"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "<div>\n",
+ "<img src=\"attachment:assert.png\" width=\"600\"/>\n",
+ "</div>"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Let's improvise error handling in pizza analyzer\n",
+ "- using `assert`:\n",
+ " - `assert` that radius is positive\n",
+ " - `assert` that slice count is positive"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 14,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "# Copy pasted code (not a typical thing which I will ask you to do) \n",
+ "# change function definitions to v2 and add the assert statements\n",
+ "\n",
+ "def pizza_size_v2(radius):\n",
+ " # TODO add assert statement here\n",
+ " assert radius >= 0\n",
+ " return (radius ** 2) * math.pi\n",
+ "\n",
+ "def slice_size_v2(radius, slice_count):\n",
+ " # TODO add assert statement here\n",
+ " assert slice_count >= 1\n",
+ " total_size = pizza_size_v2(radius)\n",
+ " return total_size * (1 / slice_count)\n",
+ "\n",
+ "def main_v2():\n",
+ " for i in range(3):\n",
+ " # grab input\n",
+ " args = input(\"Enter pizza diameter(inches), slice count: \")\n",
+ " args = args.split(',')\n",
+ " radius = float(args[0].strip()) / 2\n",
+ " slices = int(args[1].strip())\n",
+ "\n",
+ " # pizza analysis\n",
+ " size = slice_size_v2(radius, slices)\n",
+ " print('PIZZA: radius = {}, slices = {}, slice square inches = {}'\n",
+ " .format(radius, slices, size))"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Try these problematic inputs for the main() function invocation\n",
+ "\n",
+ "- 10, -4: Semantic error\n",
+ "- -10, 4: Semantic error (scariest error for this example)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 15,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Enter pizza diameter(inches), slice count: -10, 4\n"
+ ]
+ },
+ {
+ "ename": "AssertionError",
+ "evalue": "",
+ "output_type": "error",
+ "traceback": [
+ "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+ "\u001b[0;31mAssertionError\u001b[0m Traceback (most recent call last)",
+ "Cell \u001b[0;32mIn[15], line 1\u001b[0m\n\u001b[0;32m----> 1\u001b[0m \u001b[43mmain_v2\u001b[49m\u001b[43m(\u001b[49m\u001b[43m)\u001b[49m\n",
+ "Cell \u001b[0;32mIn[14], line 24\u001b[0m, in \u001b[0;36mmain_v2\u001b[0;34m()\u001b[0m\n\u001b[1;32m 21\u001b[0m slices \u001b[38;5;241m=\u001b[39m \u001b[38;5;28mint\u001b[39m(args[\u001b[38;5;241m1\u001b[39m]\u001b[38;5;241m.\u001b[39mstrip())\n\u001b[1;32m 23\u001b[0m \u001b[38;5;66;03m# pizza analysis\u001b[39;00m\n\u001b[0;32m---> 24\u001b[0m size \u001b[38;5;241m=\u001b[39m \u001b[43mslice_size_v2\u001b[49m\u001b[43m(\u001b[49m\u001b[43mradius\u001b[49m\u001b[43m,\u001b[49m\u001b[43m \u001b[49m\u001b[43mslices\u001b[49m\u001b[43m)\u001b[49m\n\u001b[1;32m 25\u001b[0m \u001b[38;5;28mprint\u001b[39m(\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mPIZZA: radius = \u001b[39m\u001b[38;5;132;01m{}\u001b[39;00m\u001b[38;5;124m, slices = \u001b[39m\u001b[38;5;132;01m{}\u001b[39;00m\u001b[38;5;124m, slice square inches = \u001b[39m\u001b[38;5;132;01m{}\u001b[39;00m\u001b[38;5;124m'\u001b[39m\n\u001b[1;32m 26\u001b[0m \u001b[38;5;241m.\u001b[39mformat(radius, slices, size))\n",
+ "Cell \u001b[0;32mIn[14], line 12\u001b[0m, in \u001b[0;36mslice_size_v2\u001b[0;34m(radius, slice_count)\u001b[0m\n\u001b[1;32m 9\u001b[0m \u001b[38;5;28;01mdef\u001b[39;00m \u001b[38;5;21mslice_size_v2\u001b[39m(radius, slice_count):\n\u001b[1;32m 10\u001b[0m \u001b[38;5;66;03m# TODO add assert statement here\u001b[39;00m\n\u001b[1;32m 11\u001b[0m \u001b[38;5;28;01massert\u001b[39;00m slice_count \u001b[38;5;241m>\u001b[39m\u001b[38;5;241m=\u001b[39m \u001b[38;5;241m1\u001b[39m\n\u001b[0;32m---> 12\u001b[0m total_size \u001b[38;5;241m=\u001b[39m \u001b[43mpizza_size_v2\u001b[49m\u001b[43m(\u001b[49m\u001b[43mradius\u001b[49m\u001b[43m)\u001b[49m\n\u001b[1;32m 13\u001b[0m \u001b[38;5;28;01mreturn\u001b[39;00m total_size \u001b[38;5;241m*\u001b[39m (\u001b[38;5;241m1\u001b[39m \u001b[38;5;241m/\u001b[39m slice_count)\n",
+ "Cell \u001b[0;32mIn[14], line 6\u001b[0m, in \u001b[0;36mpizza_size_v2\u001b[0;34m(radius)\u001b[0m\n\u001b[1;32m 4\u001b[0m \u001b[38;5;28;01mdef\u001b[39;00m \u001b[38;5;21mpizza_size_v2\u001b[39m(radius):\n\u001b[1;32m 5\u001b[0m \u001b[38;5;66;03m# TODO add assert statement here\u001b[39;00m\n\u001b[0;32m----> 6\u001b[0m \u001b[38;5;28;01massert\u001b[39;00m radius \u001b[38;5;241m>\u001b[39m\u001b[38;5;241m=\u001b[39m \u001b[38;5;241m0\u001b[39m\n\u001b[1;32m 7\u001b[0m \u001b[38;5;28;01mreturn\u001b[39;00m (radius \u001b[38;5;241m*\u001b[39m\u001b[38;5;241m*\u001b[39m \u001b[38;5;241m2\u001b[39m) \u001b[38;5;241m*\u001b[39m math\u001b[38;5;241m.\u001b[39mpi\n",
+ "\u001b[0;31mAssertionError\u001b[0m: "
+ ]
+ }
+ ],
+ "source": [
+ "main_v2()"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## What if we want to keep running even if there is an error?\n",
+ "\n",
+ "That is, we don't want to pause the program execution for user's incorrect input"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "## try / except blocks\n",
+ "\n",
+ "- `try` and `except` blocks come in pairs (runtime errors are “exceptions”)\n",
+ "- Python tries to run the code in the `try` block. \n",
+ " - If there is an exception, `try` block execution terminates and then `except` block gets executed(instead of crashing). This is called “catching” the exception.\n",
+ " - If there is no exception, `except` block doesn't get executed.\n",
+ "- Syntax (example):\n",
+ "```python\n",
+ "try:\n",
+ " flaky_function()\n",
+ "except:\n",
+ " print(\"error!\") # or some other handling\n",
+ "```"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### try / except examples\n",
+ "Try these examples using PythonTutor"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Example 1: v1"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "try:\n",
+ " print(\"2 inverse is\", 1/2)\n",
+ " print(\"1 inverse is\", 1/1)\n",
+ " print(\"0 inverse is\", 1/0)\n",
+ " print(\"-1 inverse is\", -1/1)\n",
+ " print(\"-2 inverse is\", -1/1)\n",
+ "except:\n",
+ " print(\"that's all, folks!\")"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Example 1: v2"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 16,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "2 inverse is 0.5\n",
+ "1 inverse is 1.0\n",
+ "that's all, folks!\n",
+ "-1 inverse is -1.0\n",
+ "-2 inverse is -1.0\n"
+ ]
+ }
+ ],
+ "source": [
+ "try:\n",
+ " print(\"2 inverse is\", 1/2)\n",
+ " print(\"1 inverse is\", 1/1)\n",
+ " print(\"0 inverse is\", 1/0)\n",
+ "except:\n",
+ " print(\"that's all, folks!\")\n",
+ "\n",
+ "try:\n",
+ " print(\"-1 inverse is\", -1/1)\n",
+ " print(\"-2 inverse is\", -1/1)\n",
+ "except:\n",
+ " print(\"This will never get executed!\")"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Example 2: v1\n",
+ "- hierarchy of catching exceptions"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 17,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "f: let's call g\n",
+ "g: before buggy\n",
+ "buggy: about to fail\n",
+ "f: that didn't go so well\n"
+ ]
+ }
+ ],
+ "source": [
+ "def buggy():\n",
+ " print(\"buggy: about to fail\")\n",
+ " print(\"buggy: infinity is \", 1/0)\n",
+ " print(\"buggy: oops!\") # never prints\n",
+ "\n",
+ "def g():\n",
+ " print(\"g: before buggy\")\n",
+ " buggy()\n",
+ " print(\"g: after buggy\") # never prints\n",
+ "\n",
+ "def f():\n",
+ " try:\n",
+ " print(\"f: let's call g\")\n",
+ " g()\n",
+ " print(\"f: g returned normally\") # never prints\n",
+ " except:\n",
+ " print(\"f: that didn't go so well\")\n",
+ "\n",
+ "f()"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Example 2: v2\n",
+ "- hierarchy of catching exceptions"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 18,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "f: let's call g\n",
+ "g: before buggy\n",
+ "buggy: about to fail\n",
+ "g: that didn't go well\n",
+ "g: after buggy\n",
+ "f: g returned normally\n"
+ ]
+ }
+ ],
+ "source": [
+ "def buggy():\n",
+ " print(\"buggy: about to fail\")\n",
+ " print(\"buggy: infinity is \", 1/0)\n",
+ " print(\"buggy: oops!\") # never prints\n",
+ "\n",
+ "def g():\n",
+ " print(\"g: before buggy\")\n",
+ " try:\n",
+ " buggy()\n",
+ " except:\n",
+ " print(\"g: that didn't go well\")\n",
+ " print(\"g: after buggy\") \n",
+ "\n",
+ "def f():\n",
+ " try:\n",
+ " print(\"f: let's call g\")\n",
+ " g()\n",
+ " print(\"f: g returned normally\") \n",
+ " except:\n",
+ " print(\"f: that didn't go so well\") # never prints\n",
+ "\n",
+ "f()"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Example 2: v3\n",
+ "- hierarchy of catching exceptions"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 19,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "f: let's call g\n",
+ "g: before buggy\n",
+ "buggy: about to fail\n",
+ "buggy: oops!\n",
+ "g: after buggy\n",
+ "f: g returned normally\n"
+ ]
+ }
+ ],
+ "source": [
+ "def buggy():\n",
+ " try:\n",
+ " print(\"buggy: about to fail\")\n",
+ " print(\"buggy: infinity is \", 1/0)\n",
+ " except:\n",
+ " print(\"buggy: oops!\") \n",
+ "\n",
+ "def g():\n",
+ " print(\"g: before buggy\")\n",
+ " try:\n",
+ " buggy()\n",
+ " except:\n",
+ " print(\"g: that didn't go well\") # never prints\n",
+ " print(\"g: after buggy\")\n",
+ "\n",
+ "def f():\n",
+ " try:\n",
+ " print(\"f: let's call g\")\n",
+ " g()\n",
+ " print(\"f: g returned normally\") \n",
+ " except:\n",
+ " print(\"f: that didn't go so well\") # never prints\n",
+ "\n",
+ "f()"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### What if we want to know the reason for the exception?\n",
+ "\n",
+ "- Syntax (example):\n",
+ "```python\n",
+ "try:\n",
+ " flaky_function()\n",
+ "except Exception as e:\n",
+ " print(\"error because:\", str(e))\n",
+ " print(\"type of exception:\", type(e))\n",
+ "```\n",
+ "- `Exception` is a type.\n",
+ "- e an object instance of of type `Exception` (very general)\n",
+ " - there are different types of exceptions\n",
+ "- `str(e)` gives you the reason for the exception.\n",
+ "- `type(e)` will give you the type of the exception."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Let's improvise error handling in pizza analyzer more\n",
+ "- using `try` ... `except` ... "
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 24,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "def main_v3():\n",
+ " for i in range(3):\n",
+ " # grab input\n",
+ " args = input(\"Enter pizza diameter(inches), slice count: \")\n",
+ " args = args.split(',')\n",
+ "\n",
+ "\n",
+ " # pizza analysis TODO add try/except here\n",
+ " try:\n",
+ " radius = float(args[0].strip()) / 2\n",
+ " slices = int(args[1].strip())\n",
+ " size = slice_size_v2(radius, slices)\n",
+ " print('PIZZA: radius = {}, slices = {}, slice square inches = {}'\n",
+ " .format(radius, slices, size))\n",
+ " except Exception as e:\n",
+ " print(\"error because: \",str(e))\n",
+ " print(\"type of error: \", type(e))"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+ "source": []
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Try these problematic inputs for the main() function invocation\n",
+ "\n",
+ "- 10, 0: ZeroDivisionError\n",
+ "- 10: IndexError\n",
+ "- 10, hello: ValueError\n",
+ "- 10, 4.5: ValueError\n",
+ "- 10, -4: AssertionError (after we wrote assert statement)\n",
+ "- -10, 4: AssertionError (after we wrote assert statement)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 25,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Enter pizza diameter(inches), slice count: 10,4.5\n",
+ "error because: invalid literal for int() with base 10: '4.5'\n",
+ "type of error: <class 'ValueError'>\n",
+ "Enter pizza diameter(inches), slice count: 10, -4\n",
+ "error because: \n",
+ "type of error: <class 'AssertionError'>\n",
+ "Enter pizza diameter(inches), slice count: 10, 0\n",
+ "error because: \n",
+ "type of error: <class 'AssertionError'>\n"
+ ]
+ }
+ ],
+ "source": [
+ "main_v3()"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### `Exception` is too broad\n",
+ "- it catches many types of exceptions\n",
+ "- you do not want your except block to catch every possible exception!"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 26,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "# Let's create an intentional SyntaxError\n",
+ "\n",
+ "def main_v4():\n",
+ " for i in range(5):\n",
+ " try:\n",
+ " # grab input\n",
+ " args = input(\"Enter pizza diameter(inches), slice count: \")\n",
+ " args = argssssss.split(',')\n",
+ " radius = float(args[0].strip()) / 2\n",
+ " slices = int(args[1].strip())\n",
+ " except Exception as e:\n",
+ " print(\"Bad input & reason is:\", str(e))\n",
+ " print(\"Type of exception:\", type(e))\n",
+ " \n",
+ " try:\n",
+ " # pizza analysis\n",
+ " size = slice_size_v2(radius, slices)\n",
+ " print('PIZZA: radius = {}, slices = {}, slice square inches = {}'\n",
+ " .format(radius, slices, size))\n",
+ " except Exception as e:\n",
+ " print(\"Pizza analysis error & reason is:\", str(e))\n",
+ " print(\"Type of exception:\", type(e))"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 27,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Enter pizza diameter(inches), slice count: 10,4\n",
+ "Bad input & reason is: name 'argssssss' is not defined\n",
+ "Type of exception: <class 'NameError'>\n",
+ "Pizza analysis error & reason is: local variable 'radius' referenced before assignment\n",
+ "Type of exception: <class 'UnboundLocalError'>\n"
+ ]
+ },
+ {
+ "ename": "KeyboardInterrupt",
+ "evalue": "Interrupted by user",
+ "output_type": "error",
+ "traceback": [
+ "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+ "\u001b[0;31mKeyboardInterrupt\u001b[0m Traceback (most recent call last)",
+ "Cell \u001b[0;32mIn[27], line 1\u001b[0m\n\u001b[0;32m----> 1\u001b[0m \u001b[43mmain_v4\u001b[49m\u001b[43m(\u001b[49m\u001b[43m)\u001b[49m \u001b[38;5;66;03m# oops, we made our program way too robus!\u001b[39;00m\n",
+ "Cell \u001b[0;32mIn[26], line 7\u001b[0m, in \u001b[0;36mmain_v4\u001b[0;34m()\u001b[0m\n\u001b[1;32m 4\u001b[0m \u001b[38;5;28;01mfor\u001b[39;00m i \u001b[38;5;129;01min\u001b[39;00m \u001b[38;5;28mrange\u001b[39m(\u001b[38;5;241m5\u001b[39m):\n\u001b[1;32m 5\u001b[0m \u001b[38;5;28;01mtry\u001b[39;00m:\n\u001b[1;32m 6\u001b[0m \u001b[38;5;66;03m# grab input\u001b[39;00m\n\u001b[0;32m----> 7\u001b[0m args \u001b[38;5;241m=\u001b[39m \u001b[38;5;28;43minput\u001b[39;49m\u001b[43m(\u001b[49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[38;5;124;43mEnter pizza diameter(inches), slice count: \u001b[39;49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[43m)\u001b[49m\n\u001b[1;32m 8\u001b[0m args \u001b[38;5;241m=\u001b[39m argssssss\u001b[38;5;241m.\u001b[39msplit(\u001b[38;5;124m'\u001b[39m\u001b[38;5;124m,\u001b[39m\u001b[38;5;124m'\u001b[39m)\n\u001b[1;32m 9\u001b[0m radius \u001b[38;5;241m=\u001b[39m \u001b[38;5;28mfloat\u001b[39m(args[\u001b[38;5;241m0\u001b[39m]\u001b[38;5;241m.\u001b[39mstrip()) \u001b[38;5;241m/\u001b[39m \u001b[38;5;241m2\u001b[39m\n",
+ "File \u001b[0;32m~/miniforge3/lib/python3.10/site-packages/ipykernel/kernelbase.py:1191\u001b[0m, in \u001b[0;36mKernel.raw_input\u001b[0;34m(self, prompt)\u001b[0m\n\u001b[1;32m 1189\u001b[0m msg \u001b[38;5;241m=\u001b[39m \u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mraw_input was called, but this frontend does not support input requests.\u001b[39m\u001b[38;5;124m\"\u001b[39m\n\u001b[1;32m 1190\u001b[0m \u001b[38;5;28;01mraise\u001b[39;00m StdinNotImplementedError(msg)\n\u001b[0;32m-> 1191\u001b[0m \u001b[38;5;28;01mreturn\u001b[39;00m \u001b[38;5;28;43mself\u001b[39;49m\u001b[38;5;241;43m.\u001b[39;49m\u001b[43m_input_request\u001b[49m\u001b[43m(\u001b[49m\n\u001b[1;32m 1192\u001b[0m \u001b[43m \u001b[49m\u001b[38;5;28;43mstr\u001b[39;49m\u001b[43m(\u001b[49m\u001b[43mprompt\u001b[49m\u001b[43m)\u001b[49m\u001b[43m,\u001b[49m\n\u001b[1;32m 1193\u001b[0m \u001b[43m \u001b[49m\u001b[38;5;28;43mself\u001b[39;49m\u001b[38;5;241;43m.\u001b[39;49m\u001b[43m_parent_ident\u001b[49m\u001b[43m[\u001b[49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[38;5;124;43mshell\u001b[39;49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[43m]\u001b[49m\u001b[43m,\u001b[49m\n\u001b[1;32m 1194\u001b[0m \u001b[43m \u001b[49m\u001b[38;5;28;43mself\u001b[39;49m\u001b[38;5;241;43m.\u001b[39;49m\u001b[43mget_parent\u001b[49m\u001b[43m(\u001b[49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[38;5;124;43mshell\u001b[39;49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[43m)\u001b[49m\u001b[43m,\u001b[49m\n\u001b[1;32m 1195\u001b[0m \u001b[43m \u001b[49m\u001b[43mpassword\u001b[49m\u001b[38;5;241;43m=\u001b[39;49m\u001b[38;5;28;43;01mFalse\u001b[39;49;00m\u001b[43m,\u001b[49m\n\u001b[1;32m 1196\u001b[0m \u001b[43m\u001b[49m\u001b[43m)\u001b[49m\n",
+ "File \u001b[0;32m~/miniforge3/lib/python3.10/site-packages/ipykernel/kernelbase.py:1234\u001b[0m, in \u001b[0;36mKernel._input_request\u001b[0;34m(self, prompt, ident, parent, password)\u001b[0m\n\u001b[1;32m 1231\u001b[0m \u001b[38;5;28;01mexcept\u001b[39;00m \u001b[38;5;167;01mKeyboardInterrupt\u001b[39;00m:\n\u001b[1;32m 1232\u001b[0m \u001b[38;5;66;03m# re-raise KeyboardInterrupt, to truncate traceback\u001b[39;00m\n\u001b[1;32m 1233\u001b[0m msg \u001b[38;5;241m=\u001b[39m \u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mInterrupted by user\u001b[39m\u001b[38;5;124m\"\u001b[39m\n\u001b[0;32m-> 1234\u001b[0m \u001b[38;5;28;01mraise\u001b[39;00m \u001b[38;5;167;01mKeyboardInterrupt\u001b[39;00m(msg) \u001b[38;5;28;01mfrom\u001b[39;00m \u001b[38;5;28;01mNone\u001b[39;00m\n\u001b[1;32m 1235\u001b[0m \u001b[38;5;28;01mexcept\u001b[39;00m \u001b[38;5;167;01mException\u001b[39;00m:\n\u001b[1;32m 1236\u001b[0m \u001b[38;5;28mself\u001b[39m\u001b[38;5;241m.\u001b[39mlog\u001b[38;5;241m.\u001b[39mwarning(\u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mInvalid Message:\u001b[39m\u001b[38;5;124m\"\u001b[39m, exc_info\u001b[38;5;241m=\u001b[39m\u001b[38;5;28;01mTrue\u001b[39;00m)\n",
+ "\u001b[0;31mKeyboardInterrupt\u001b[0m: Interrupted by user"
+ ]
+ }
+ ],
+ "source": [
+ "main_v4() # oops, we made our program way too robus!\n",
+ "\n",
+ "# In this case, it's a syntax error, so the program will never work\n",
+ "# We want the program to crash so that we know we have to fix it"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### How can we make `except` block catch specific exceptions?\n",
+ "\n",
+ "- Syntax (example):\n",
+ "```python\n",
+ "try:\n",
+ " flaky_function()\n",
+ "except (ValueError, IndexError) as e:\n",
+ " print(\"error because:\", str(e))\n",
+ " print(\"type of exception:\", type(e))\n",
+ "```"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 30,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "# Let's fix our except blocks\n",
+ "# Try introducing the intentional SyntaxError now\n",
+ "\n",
+ "def main_v5():\n",
+ " for i in range(5):\n",
+ " try:\n",
+ " # grab input\n",
+ " args = input(\"Enter pizza diameter(inches), slice count: \")\n",
+ " args = argssssssss.split(',')\n",
+ " radius = float(args[0].strip()) / 2\n",
+ " slices = int(args[1].strip())\n",
+ " except (ValueError, IndexError) as e:\n",
+ " print(\"Bad input & reason is:\", str(e))\n",
+ " print(\"Type of exception:\", type(e))\n",
+ " continue\n",
+ " \n",
+ " try:\n",
+ " # pizza analysis\n",
+ " size = slice_size_v2(radius, slices)\n",
+ " print('PIZZA: radius = {}, slices = {}, slice square inches = {}'\n",
+ " .format(radius, slices, size))\n",
+ " except Exception as e:\n",
+ " print(\"Pizza analysis error & reason is:\", str(e))\n",
+ " print(\"Type of exception:\", type(e))"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Try these problematic inputs for the main() function invocation\n",
+ "\n",
+ "- 10, 0: ZeroDivisionError\n",
+ "- 10: IndexError\n",
+ "- 10, hello: ValueError\n",
+ "- 10, 4.5: ValueError\n",
+ "- 10, -4: AssertionError (after we wrote assert statement)\n",
+ "- -10, 4: AssertionError (after we wrote assert statement)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 31,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Enter pizza diameter(inches), slice count: 10,4.5\n"
+ ]
+ },
+ {
+ "ename": "NameError",
+ "evalue": "name 'argssssssss' is not defined",
+ "output_type": "error",
+ "traceback": [
+ "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+ "\u001b[0;31mNameError\u001b[0m Traceback (most recent call last)",
+ "Cell \u001b[0;32mIn[31], line 1\u001b[0m\n\u001b[0;32m----> 1\u001b[0m \u001b[43mmain_v5\u001b[49m\u001b[43m(\u001b[49m\u001b[43m)\u001b[49m\n",
+ "Cell \u001b[0;32mIn[30], line 9\u001b[0m, in \u001b[0;36mmain_v5\u001b[0;34m()\u001b[0m\n\u001b[1;32m 6\u001b[0m \u001b[38;5;28;01mtry\u001b[39;00m:\n\u001b[1;32m 7\u001b[0m \u001b[38;5;66;03m# grab input\u001b[39;00m\n\u001b[1;32m 8\u001b[0m args \u001b[38;5;241m=\u001b[39m \u001b[38;5;28minput\u001b[39m(\u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mEnter pizza diameter(inches), slice count: \u001b[39m\u001b[38;5;124m\"\u001b[39m)\n\u001b[0;32m----> 9\u001b[0m args \u001b[38;5;241m=\u001b[39m \u001b[43margssssssss\u001b[49m\u001b[38;5;241m.\u001b[39msplit(\u001b[38;5;124m'\u001b[39m\u001b[38;5;124m,\u001b[39m\u001b[38;5;124m'\u001b[39m)\n\u001b[1;32m 10\u001b[0m radius \u001b[38;5;241m=\u001b[39m \u001b[38;5;28mfloat\u001b[39m(args[\u001b[38;5;241m0\u001b[39m]\u001b[38;5;241m.\u001b[39mstrip()) \u001b[38;5;241m/\u001b[39m \u001b[38;5;241m2\u001b[39m\n\u001b[1;32m 11\u001b[0m slices \u001b[38;5;241m=\u001b[39m \u001b[38;5;28mint\u001b[39m(args[\u001b[38;5;241m1\u001b[39m]\u001b[38;5;241m.\u001b[39mstrip())\n",
+ "\u001b[0;31mNameError\u001b[0m: name 'argssssssss' is not defined"
+ ]
+ }
+ ],
+ "source": [
+ "main_v5()\n"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Exception hierarchy\n",
+ "- It helps to know some common excpeptions and to know their hierarchy.\n",
+ "- Don't try to memorize this but do make a note of the exceptions that occur the most often.\n",
+ "- Python documentation: https://docs.python.org/3/library/exceptions.html."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### `raise` statements\n",
+ "- Rather than using assert we can also raise a specific error. \n",
+ "\n",
+ "- Syntax (example):\n",
+ "```python\n",
+ "if BOOLEAN_CONDITION:\n",
+ " raise ArithmeticError(\"details of error\")\n",
+ "```\n",
+ "\n",
+ "<div>\n",
+ "<img src=\"attachment:raise.png\" width=\"500\"/>\n",
+ "</div>"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 32,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "enter your age: -5\n"
+ ]
+ },
+ {
+ "ename": "ArithmeticError",
+ "evalue": "age can't be negative",
+ "output_type": "error",
+ "traceback": [
+ "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+ "\u001b[0;31mArithmeticError\u001b[0m Traceback (most recent call last)",
+ "Cell \u001b[0;32mIn[32], line 6\u001b[0m\n\u001b[1;32m 4\u001b[0m \u001b[38;5;66;03m# previously: assert a >= 0\u001b[39;00m\n\u001b[1;32m 5\u001b[0m \u001b[38;5;28;01mif\u001b[39;00m age \u001b[38;5;241m<\u001b[39m \u001b[38;5;241m0\u001b[39m:\n\u001b[0;32m----> 6\u001b[0m \u001b[38;5;28;01mraise\u001b[39;00m \u001b[38;5;167;01mArithmeticError\u001b[39;00m(\u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mage can\u001b[39m\u001b[38;5;124m'\u001b[39m\u001b[38;5;124mt be negative\u001b[39m\u001b[38;5;124m\"\u001b[39m) \u001b[38;5;66;03m# we can 'raise' a relevant exception\u001b[39;00m\n\u001b[1;32m 7\u001b[0m \u001b[38;5;28mprint\u001b[39m(\u001b[38;5;124m\"\u001b[39m\u001b[38;5;124min five years you will be\u001b[39m\u001b[38;5;124m\"\u001b[39m, age \u001b[38;5;241m+\u001b[39m \u001b[38;5;241m5\u001b[39m, \u001b[38;5;124m\"\u001b[39m\u001b[38;5;124myears old\u001b[39m\u001b[38;5;124m\"\u001b[39m) \n",
+ "\u001b[0;31mArithmeticError\u001b[0m: age can't be negative"
+ ]
+ }
+ ],
+ "source": [
+ "# simple example: raise exceptions instead of using assert statements\n",
+ "\n",
+ "age = int(input(\"enter your age: \"))\n",
+ "# previously: assert a >= 0\n",
+ "if age < 0:\n",
+ " raise ArithmeticError(\"age can't be negative\") # we can 'raise' a relevant exception\n",
+ "print(\"in five years you will be\", age + 5, \"years old\") "
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 33,
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "\n",
+ "def pizza_size_v2(radius):\n",
+ " assert radius >= 0\n",
+ " return (radius ** 2) * math.pi\n",
+ "\n",
+ "def slice_size_v2(radius, slice_count):\n",
+ " assert slice_count >= 0\n",
+ " total_size = pizza_size_v2(radius)\n",
+ " return total_size * (1 / slice_count)\n",
+ "\n",
+ "def main_v6():\n",
+ " for i in range(5):\n",
+ " # grab input\n",
+ " try:\n",
+ " args = input(\"Enter pizza diameter(inches), slice count: \")\n",
+ " args = args.split(',')\n",
+ " radius = float(args[0].strip()) / 2\n",
+ " slices = int(args[1].strip())\n",
+ " except (ValueError, TypeError, IndexError) as e:\n",
+ " print(\"Bad input & reason is:\", str(e))\n",
+ " print(\"Type of exception:\", type(e))\n",
+ " continue\n",
+ "\n",
+ " # pizza analysis\n",
+ " try:\n",
+ " size = slice_size_v2(radius, slices)\n",
+ " print('PIZZA: radius={}, slices={}, slice square inches={}'\n",
+ " .format(radius, slices, size))\n",
+ " except (ZeroDivisionError, AssertionError) as e:\n",
+ " print(\"Pizza analysis error!\", str(e))\n",
+ " print(\"Type of exception:\", type(e))"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "metadata": {},
+ "source": [
+ "### Try these problematic inputs for the main() function invocation\n",
+ "\n",
+ "- 10, -4: ArithmeticError (after we wrote assert statement)\n",
+ "- -10, 4: ArithmeticError (after we wrote assert statement)"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 34,
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Enter pizza diameter(inches), slice count: 20,0\n",
+ "Pizza analysis error! division by zero\n",
+ "Type of exception: <class 'ZeroDivisionError'>\n"
+ ]
+ },
+ {
+ "ename": "KeyboardInterrupt",
+ "evalue": "Interrupted by user",
+ "output_type": "error",
+ "traceback": [
+ "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+ "\u001b[0;31mKeyboardInterrupt\u001b[0m Traceback (most recent call last)",
+ "Cell \u001b[0;32mIn[34], line 1\u001b[0m\n\u001b[0;32m----> 1\u001b[0m \u001b[43mmain_v6\u001b[49m\u001b[43m(\u001b[49m\u001b[43m)\u001b[49m\n",
+ "Cell \u001b[0;32mIn[33], line 14\u001b[0m, in \u001b[0;36mmain_v6\u001b[0;34m()\u001b[0m\n\u001b[1;32m 11\u001b[0m \u001b[38;5;28;01mfor\u001b[39;00m i \u001b[38;5;129;01min\u001b[39;00m \u001b[38;5;28mrange\u001b[39m(\u001b[38;5;241m5\u001b[39m):\n\u001b[1;32m 12\u001b[0m \u001b[38;5;66;03m# grab input\u001b[39;00m\n\u001b[1;32m 13\u001b[0m \u001b[38;5;28;01mtry\u001b[39;00m:\n\u001b[0;32m---> 14\u001b[0m args \u001b[38;5;241m=\u001b[39m \u001b[38;5;28;43minput\u001b[39;49m\u001b[43m(\u001b[49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[38;5;124;43mEnter pizza diameter(inches), slice count: \u001b[39;49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[43m)\u001b[49m\n\u001b[1;32m 15\u001b[0m args \u001b[38;5;241m=\u001b[39m args\u001b[38;5;241m.\u001b[39msplit(\u001b[38;5;124m'\u001b[39m\u001b[38;5;124m,\u001b[39m\u001b[38;5;124m'\u001b[39m)\n\u001b[1;32m 16\u001b[0m radius \u001b[38;5;241m=\u001b[39m \u001b[38;5;28mfloat\u001b[39m(args[\u001b[38;5;241m0\u001b[39m]\u001b[38;5;241m.\u001b[39mstrip()) \u001b[38;5;241m/\u001b[39m \u001b[38;5;241m2\u001b[39m\n",
+ "File \u001b[0;32m~/miniforge3/lib/python3.10/site-packages/ipykernel/kernelbase.py:1191\u001b[0m, in \u001b[0;36mKernel.raw_input\u001b[0;34m(self, prompt)\u001b[0m\n\u001b[1;32m 1189\u001b[0m msg \u001b[38;5;241m=\u001b[39m \u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mraw_input was called, but this frontend does not support input requests.\u001b[39m\u001b[38;5;124m\"\u001b[39m\n\u001b[1;32m 1190\u001b[0m \u001b[38;5;28;01mraise\u001b[39;00m StdinNotImplementedError(msg)\n\u001b[0;32m-> 1191\u001b[0m \u001b[38;5;28;01mreturn\u001b[39;00m \u001b[38;5;28;43mself\u001b[39;49m\u001b[38;5;241;43m.\u001b[39;49m\u001b[43m_input_request\u001b[49m\u001b[43m(\u001b[49m\n\u001b[1;32m 1192\u001b[0m \u001b[43m \u001b[49m\u001b[38;5;28;43mstr\u001b[39;49m\u001b[43m(\u001b[49m\u001b[43mprompt\u001b[49m\u001b[43m)\u001b[49m\u001b[43m,\u001b[49m\n\u001b[1;32m 1193\u001b[0m \u001b[43m \u001b[49m\u001b[38;5;28;43mself\u001b[39;49m\u001b[38;5;241;43m.\u001b[39;49m\u001b[43m_parent_ident\u001b[49m\u001b[43m[\u001b[49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[38;5;124;43mshell\u001b[39;49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[43m]\u001b[49m\u001b[43m,\u001b[49m\n\u001b[1;32m 1194\u001b[0m \u001b[43m \u001b[49m\u001b[38;5;28;43mself\u001b[39;49m\u001b[38;5;241;43m.\u001b[39;49m\u001b[43mget_parent\u001b[49m\u001b[43m(\u001b[49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[38;5;124;43mshell\u001b[39;49m\u001b[38;5;124;43m\"\u001b[39;49m\u001b[43m)\u001b[49m\u001b[43m,\u001b[49m\n\u001b[1;32m 1195\u001b[0m \u001b[43m \u001b[49m\u001b[43mpassword\u001b[49m\u001b[38;5;241;43m=\u001b[39;49m\u001b[38;5;28;43;01mFalse\u001b[39;49;00m\u001b[43m,\u001b[49m\n\u001b[1;32m 1196\u001b[0m \u001b[43m\u001b[49m\u001b[43m)\u001b[49m\n",
+ "File \u001b[0;32m~/miniforge3/lib/python3.10/site-packages/ipykernel/kernelbase.py:1234\u001b[0m, in \u001b[0;36mKernel._input_request\u001b[0;34m(self, prompt, ident, parent, password)\u001b[0m\n\u001b[1;32m 1231\u001b[0m \u001b[38;5;28;01mexcept\u001b[39;00m \u001b[38;5;167;01mKeyboardInterrupt\u001b[39;00m:\n\u001b[1;32m 1232\u001b[0m \u001b[38;5;66;03m# re-raise KeyboardInterrupt, to truncate traceback\u001b[39;00m\n\u001b[1;32m 1233\u001b[0m msg \u001b[38;5;241m=\u001b[39m \u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mInterrupted by user\u001b[39m\u001b[38;5;124m\"\u001b[39m\n\u001b[0;32m-> 1234\u001b[0m \u001b[38;5;28;01mraise\u001b[39;00m \u001b[38;5;167;01mKeyboardInterrupt\u001b[39;00m(msg) \u001b[38;5;28;01mfrom\u001b[39;00m \u001b[38;5;28;01mNone\u001b[39;00m\n\u001b[1;32m 1235\u001b[0m \u001b[38;5;28;01mexcept\u001b[39;00m \u001b[38;5;167;01mException\u001b[39;00m:\n\u001b[1;32m 1236\u001b[0m \u001b[38;5;28mself\u001b[39m\u001b[38;5;241m.\u001b[39mlog\u001b[38;5;241m.\u001b[39mwarning(\u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mInvalid Message:\u001b[39m\u001b[38;5;124m\"\u001b[39m, exc_info\u001b[38;5;241m=\u001b[39m\u001b[38;5;28;01mTrue\u001b[39;00m)\n",
+ "\u001b[0;31mKeyboardInterrupt\u001b[0m: Interrupted by user"
+ ]
+ }
+ ],
+ "source": [
+ "main_v6()"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": null,
+ "metadata": {},
+ "outputs": [],
+ "source": []
+ }
+ ],
+ "metadata": {
+ "kernelspec": {
+ "display_name": "Python 3 (ipykernel)",
+ "language": "python",
+ "name": "python3"
+ },
+ "language_info": {
+ "codemirror_mode": {
+ "name": "ipython",
+ "version": 3
+ },
+ "file_extension": ".py",
+ "mimetype": "text/x-python",
+ "name": "python",
+ "nbconvert_exporter": "python",
+ "pygments_lexer": "ipython3",
+ "version": "3.10.6"
+ }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 4
+}
--
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