{
"metadata": {
"name": "",
"signature": "sha256:636fe844c88ef46d09064f199c6b3a4c62e262611a41cc6f126f08459b94982e"
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"worksheets": [
{
"cells": [
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h1>Chapter 17: Exception Handling<h1>"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.1, Page Number: 397<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"print \"start\"\n",
"\n",
"try: #start a try block\n",
" print \"Inside try block\"\n",
" raise Exception(99) #raise an error\n",
" print \"This will not execute\"\n",
"except Exception,i: #catch an error\n",
" print \"Caught an exception -- value is:\",\n",
" print i\n",
"\n",
"print \"end\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"start\n",
"Inside try block\n",
"Caught an exception -- value is: 99\n",
"end\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.2, Page Number: 399<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"\n",
"import sys\n",
"\n",
"\n",
"\n",
"def main():\n",
" print \"start\"\n",
" try: #start a try block\n",
" print \"Inside try block\"\n",
" raise Exception(99) #raise an error\n",
" print \"This will not execute\"\n",
" except Exception,i: #catch an error\n",
" if isinstance(i,float):\n",
" print \"Caught an exception -- value is:\",\n",
" print i\n",
" else:\n",
" print \"Abnormal program termination\"\n",
" return\n",
" print \"end\"\n",
"\n",
" \n",
"main()"
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"start\n",
"Inside try block\n",
"Abnormal program termination\n"
]
}
],
"prompt_number": 1
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.3, Page Number: 400<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"def Xtest(test):\n",
" print \"Inside Xtest, test is: \",test\n",
" if(test):\n",
" raise Exception(test)\n",
" \n",
"print \"start\"\n",
"\n",
"try: #start a try block\n",
" print \"Inside try block\"\n",
" Xtest(0)\n",
" Xtest(1)\n",
" Xtest(2)\n",
"except Exception,i: #catch an error\n",
" print \"Caught an exception -- value is:\",\n",
" print i\n",
"\n",
"print \"end\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"start\n",
"Inside try block\n",
"Inside Xtest, test is: 0\n",
"Inside Xtest, test is: 1\n",
"Caught an exception -- value is: 1\n",
"end\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.4, Page Number: 401<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"def Xhandler(test):\n",
" try:\n",
" if(test):\n",
" raise Exception(test)\n",
" except Exception,i:\n",
" print \"Caught One! Ex #:\",i\n",
" \n",
"print \"start\"\n",
"\n",
"Xhandler(1)\n",
"Xhandler(2)\n",
"Xhandler(0)\n",
"Xhandler(3)\n",
"\n",
"print \"end\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"start\n",
"Caught One! Ex #: 1\n",
"Caught One! Ex #: 2\n",
"Caught One! Ex #: 3\n",
"end\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.5, Page Number: 401<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"\n",
"class MyException:\n",
" def __init__(self,s):\n",
" self.str_what=s\n",
" \n",
"#Variable declaration\n",
"a=None \n",
"b=None\n",
"\n",
"try:\n",
" print \"Enter numerator and denominator:\"\n",
" #User-input\n",
" a=10 \n",
" b=0\n",
" if not(b):\n",
" raise MyException(\"Cannot divide by zero!\")\n",
" else:\n",
" print \"Quotient is\",a/b\n",
"except MyException as e: #catch an error\n",
" print e.str_what\n",
" "
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Enter numerator and denominator:\n",
"Cannot divide by zero!\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.6, Page Number: 403<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"class MyException:\n",
" def __init__(self,s):\n",
" self.x=s\n",
" \n",
"def Xhandler(test):\n",
" try:\n",
" if(test):\n",
" raise MyException(test)\n",
" else:\n",
" raise MyException(\"Value is zero\")\n",
" except MyException as i:\n",
" if isinstance(i.x,int):\n",
" print \"Caught One! Ex #:\",i.x\n",
" else:\n",
" print \"Caught a string:\",\n",
" print i.x\n",
" \n",
"print \"start\"\n",
"\n",
"Xhandler(1)\n",
"Xhandler(2)\n",
"Xhandler(0)\n",
"Xhandler(3)\n",
"\n",
"print \"end\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"start\n",
"Caught One! Ex #: 1\n",
"Caught One! Ex #: 2\n",
"Caught a string: Value is zero\n",
"Caught One! Ex #: 3\n",
"end\n"
]
}
],
"prompt_number": 5
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.7, Page Number: 404<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"\n",
"class B:\n",
" pass\n",
"\n",
"class D(B):\n",
" pass\n",
"\n",
"derived=D()\n",
"\n",
"try:\n",
" raise B()\n",
"except B as b:\n",
" print \"Caught a base class.\"\n",
"except D as d:\n",
" print \"This wont execute.\"\n",
" "
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Caught a base class.\n"
]
}
],
"prompt_number": 6
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.8, Page Number: 405<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"def Xhandler(test):\n",
" try:\n",
" if test==0:\n",
" raise Exception(test) #throw int\n",
" if test==1:\n",
" raise Exception('a') #throw char\n",
" if test==2:\n",
" raise Exception(123.23) #throw double\n",
" except: #Catches all exceptions\n",
" print \"Caught One!\"\n",
"\n",
"print \"start\"\n",
"\n",
"Xhandler(0)\n",
"Xhandler(1)\n",
"Xhandler(2)\n",
"\n",
"print \"end\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"start\n",
"Caught One!\n",
"Caught One!\n",
"Caught One!\n",
"end\n"
]
}
],
"prompt_number": 7
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.9, Page Number: 405<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"class MyException:\n",
" def __init__(self,s):\n",
" self.x=s\n",
" \n",
"def Xhandler(test):\n",
" try:\n",
" if test==0:\n",
" raise MyException(test) #throw int\n",
" if test==1:\n",
" raise MyException('a') #throw char\n",
" if test==2:\n",
" raise MyException(123.23) #throw double\n",
" except MyException as i:\n",
" if isinstance(i.x,int): #catch an int exception\n",
" print \"Caught\",i.x \n",
" else: #catch all other exceptions\n",
" print \"Caught One!\"\n",
" \n",
"\n",
"print \"start\"\n",
"\n",
"Xhandler(0)\n",
"Xhandler(1)\n",
"Xhandler(2)\n",
"\n",
"print \"end\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"start\n",
"Caught 0\n",
"Caught One!\n",
"Caught One!\n",
"end\n"
]
}
],
"prompt_number": 8
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.10, Page Number: 407<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"class MyException:\n",
" def __init__(self,s):\n",
" self.x=s\n",
" \n",
"#This function can only throw ints, chars and doubles\n",
"def Xhandler(test):\n",
" if test==0:\n",
" raise MyException(test) #throw int\n",
" if test==1:\n",
" raise MyException('a') #throw char\n",
" if test==2:\n",
" raise MyException(123.23) #throw double\n",
" \n",
"\n",
"print \"start\"\n",
"try:\n",
" Xhandler(0)\n",
"except MyException as i:\n",
" if isinstance(i.x,int): #catch an int exception\n",
" print \"Caught int\" \n",
" elif isinstance(i.x,str): #catch a char exception\n",
" print \"Caught char\"\n",
" elif isinstance(i.x,float): #catch a float exception\n",
" print \"Caught double\"\n",
"\n",
"print \"end\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"start\n",
"Caught int\n",
"end\n"
]
}
],
"prompt_number": 9
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.11, Page Number: 408<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"def Xhandler():\n",
" try:\n",
" raise Exception(\"hello\") #throw a char *\n",
" except Exception,c: #catch a char *\n",
" print \"Caugh char * inside Xhandler\"\n",
" raise #rethrow char * out of function\n",
" \n",
"print \"start\"\n",
"try:\n",
" Xhandler()\n",
"except Exception,c:\n",
" print \"Caught char * inside main\"\n",
" \n",
"print \"end\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"start\n",
"Caugh char * inside Xhandler\n",
"Caught char * inside main\n",
"end\n"
]
}
],
"prompt_number": 10
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.12, Page Number: 410<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"from ctypes import *\n",
"\n",
"#Variable declaration\n",
"p=[]\n",
"\n",
"try:\n",
" for i in range(32):\n",
" p.append(c_int())\n",
"except MemoryError,m:\n",
" print \"Allocation failure.\"\n",
" \n",
"for i in range(32):\n",
" p[i]=i\n",
" \n",
"for i in range(32):\n",
" print p[i],\n",
" \n",
" "
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31\n"
]
}
],
"prompt_number": 12
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.13, Page Number: 410<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"from ctypes import *\n",
"\n",
"#Variable declaration\n",
"p=[]\n",
"\n",
"\n",
"for i in range(32):\n",
" p.append(c_int()) \n",
"if not(p):\n",
" print \"Allocation failure.\"\n",
" \n",
"for i in range(32):\n",
" p[i]=i\n",
" \n",
"for i in range(32):\n",
" print p[i],\n",
" \n",
" "
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31\n"
]
}
],
"prompt_number": 13
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"<h3>Example 17.13, Page Number: 412<h3>"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"\n",
"class three_d:\n",
" def __init__(self,i=0,j=0,k=0): #3=D coordinates\n",
" if(i==0 and j==0 and k==0):\n",
" self.x=self.y=self.z=0\n",
" print \"Constructing 0, 0, 0\"\n",
" else:\n",
" self.x=i\n",
" self.y=j\n",
" self.z=k\n",
" print \"Constructing\",i,\",\",j,\",\",k\n",
" def __del__(self):\n",
" print \"Destructing\"\n",
" #new overloaded relative to three_d.\n",
" def __new__(typ, *args, **kwargs):\n",
" obj = object.__new__(typ, *args, **kwargs)\n",
" return obj\n",
" def show(self):\n",
" print self.x,\",\",\n",
" print self.y,\",\",\n",
" print self.z\n",
" \n",
"p1=[]*3\n",
"p2=[]\n",
" \n",
"try:\n",
" print \"Allocating array of three_d objects.\"\n",
" for i in range(3): #allocate array\n",
" p1.append(three_d())\n",
" print \"Allocating three_d object.\"\n",
" p2.append(three_d(5,6,7)) #allocate object\n",
"except MemoryError:\n",
" print \"Allocation error\"\n",
" \n",
"p1[2].show()\n",
"p2[0].show()\n",
"\n",
"\n",
"for i in xrange(2,-1,-1):\n",
" del p1[i] #delete array\n",
"print \"Deleting array of thee_d objects.\"\n",
"\n",
"del p2[0] #delete object\n",
"print \"Deleting three_d object.\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"Allocating array of three_d objects.\n",
"Constructing 0, 0, 0\n",
"Constructing 0, 0, 0\n",
"Constructing 0, 0, 0\n",
"Allocating three_d object.\n",
"Constructing 5 , 6 , 7\n",
"0 , 0 , 0\n",
"5 , 6 , 7\n",
"Destructing\n",
"Destructing\n",
"Destructing\n",
"Deleting array of thee_d objects.\n",
"Destructing\n",
"Deleting three_d object.\n"
]
}
],
"prompt_number": 14
},
{
"cell_type": "code",
"collapsed": false,
"input": [],
"language": "python",
"metadata": {},
"outputs": []
}
],
"metadata": {}
}
]
}