Transcript Chap 35 Python

Chapter 35 – Python
Outline
35.1
Introduction
35.1.1 First Python Program
35.1.2 Python Keywords
35.2
Basic Data Types, Control Statements and Functions
35.3
Tuples, Lists and Dictionaries
35.4
String Processing and Regular Expressions
35.5
Exception Handling
35.6
Introduction to CGI Programming
35.7
Form Processing and Business Logic
35.8
Cookies
35.9
Database Application Programming Interface (DB-API)
35.9.1 Setup
35.9.2 Simple DB-API Program
35.10
Operator Precedence Chart
35.11
Web Resources
 2004 Prentice Hall, Inc. All rights reserved.
Objectives
• In this lesson, you will learn:
– To understand basic Python data types.
– To understand string processing and regular expressions in
Python.
– To use exception handling.
– To perform basic CGI tasks in Python.
– To construct programs that interact with MySQL databases
using the Python Database Application Programming
Interface (DB-API).
 2004 Prentice Hall, Inc. All rights reserved.
35.1 Introduction
• Python
–
–
–
–
–
–
–
–
Interpreted
Cross-platform
Object-oriented
Large-scale Internet search engines
Small administration scripts
GUI applications
CGI scripts
Freely distributed
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35.1.1 First Python Program
• Python
– Can be executed on a program stored in a file
– Can run in interactive mode
• Users enter lines of code one at a time
• Enables programmers to test small blocks of code quickly
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1
# Fig. 35.1: fig35_01.py
2
# A first program in Python
3
4
Outline
print "Welcome to Python!"
Welcome to Python!
fig35_01.py
(1 of 1)
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All rights reserved.
35.1.1 First Python Program
Python 2.1 (#15, Apr 16 2001, 18:25:49) [MSC 32 bit
(Intel)] on win32
Type "copyright", "credits" or "license" for more
information.
>>> print "Welcome to Python!"
Welcome to Python!
>>> ^Z
Fig. 35.2
Python in interactive mode.
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35.1.2 Python Keywords
• Python is case-sensitive
• Keywords can be obtained from keyword module
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35.1.2 Python Keywords
Python
keywords
and
continue else
assert
def
except
break
del
exec
class
elif
finally
Fig. 35.3 Python keywords.
for
from
global
if
import
in
is
lambda
not
or
pass
print
raise
return
try
while
Python 2.1 (#15, Apr 16 2001, 18:25:49) [MSC 32 bit
(Intel)] on win32
Type "copyright", "credits" or "license" for more
information.
>>> import keyword
>>> print keyword.kwlist
['and', 'assert', 'break', 'class', 'continue', 'def',
'del', 'elif', 'else', 'except', 'exec', 'finally',
'for', 'from', 'global', 'if', 'import', 'in', 'is',
'lambda', 'not', 'or', 'pass', 'print', 'raise',
'return', 'try', 'while']
>>>
Fig. 35.4
Printing Python keywords in interactive mode.
 2004 Prentice Hall, Inc. All rights reserved.
35.2 Basic Data Types, Control Statements
and Functions
• Introduces basic data types, control statements,
and functions
– while loop
– if statement
– Modulo operator ( % )
– return keyword
– if…elif…else statement
– Line-continuation character ( \ )
– Escape sequences
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1
# Fig. 35.5: fig35_05.py
2
# Program to illustrate basic data types, control structures and
3
# functions.
Outline
4
5
6
def greatestCommonDivisor( x, y ):
gcd = min( x, y )
fig35_05.py
(1 of 2)
7
8
while gcd >= 1:
9
10
if ( x % gcd ) == ( y % gcd ) == 0:
return gcd
11
12
else:
gcd -= 1
13
14
15 def determineColor( color ):
16
17
18
19
20
21
22
if color == "green":
print "You entered green!"
elif color == "purple":
print "You entered purple!"
else:
print "You did not enter green or purple."
23
24 number1 = int( raw_input( "Enter a positive integer: " ) )
25 number2 = int( raw_input( "Enter a positive integer: " ) )
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26
27 print "The greatest common divisor is", \
28
greatestCommonDivisor( number1, number2 )
Outline
29
30 for entry in range( 5 ):
31
colorChoice = raw_input( "\nEnter your favorite color: " )
32
determineColor( colorChoice )
fig35_05.py
(2 of 2)
Enter a positive integer: 2
Enter a positive integer: 30
The greatest common divisor is 2
Enter your favorite color: yellow
You did not enter green or purple.
Enter your favorite color: green
You entered green!
Enter your favorite color: black
You did not enter green or purple.
Enter your favorite color: purple
You entered purple!
Enter your favorite color: red
You did not enter green or purple.
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All rights reserved.
35.2 Basic Data Types, Control Statements
and Functions
Meaning
Escape
sequence
\n
Newline (line feed).
\r
Carriage return.
\t
Tab.
\'
Single quote.
\"
Double quote.
\b
Backspace.
\\
Backslash.
Fig. 35.6 Escape sequences.
 2004 Prentice Hall, Inc. All rights reserved.
35.3 Tuples, Lists and Dictionaries
• list
– A sequence of related data
• Tuple
– A list whose elements may not be modified
– Immutable
– Singleton
• One-element tuple
• Dictionary
– A list of values that are accessed through their associated
keys
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1
# Fig. 35.7: fig35_07.py
2
# A program that illustrates tuples, lists and dictionaries.
Outline
3
4
# tuples
5
aTuple = ( 1, "a", 3.0 )
# create tuple
6
firstItem = aTuple[ 0 ]
# first tuple item
7
secondItem = aTuple[ 1 ]
# second tuple item
8
thirdItem = aTuple[ 2 ]
# third tuple item
fig35_07.py
(1 of 3)
9
10 print "The first item in the tuple is", firstItem
11 print "The second item in the tuple is", secondItem
12 print "The third item in the tuple is", thirdItem
13 print
14
15 firstItem, secondItem, thirdItem = aTuple
16 print "The first item in the tuple is", firstItem
17 print "The second item in the tuple is", secondItem
18 print "The third item in the tuple is", thirdItem
19 print
20
21 aTuple += ( 4, )
22 print "Used the += statement on the tuple"
23 print
24
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25 # print the tuple
26 print "The raw tuple data is:", aTuple
Outline
27 print "The items in the tuple are:"
28
29 for item in aTuple:
30
fig35_07.py
(2 of 3)
# print each item
print item,
31
32 print
# end previous line
33 print
# blank line
34
35 # lists
36 aList = [ 1, 2, 3 ]
# create list
37 aList[ 0 ] = 0
# change first element of list
38 aList.append( 5 )
# add item to end of list
39
40 print "The raw list data is:", aList
# print list data
41 print
42
43 aList += [ 4 ]
# add an item to the end of the list
44 print "Added an item to the list using the += statement"
45 print
46
47 # print each item in the list
48 print "The items in the list are:"
49
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50 for item in aList:
51
print item,
Outline
52
53 print
# end previous line
54 print
# blank line
fig35_07.py
(3 of 3)
55
56 # dictionaries
57 aDictionary = { 1 : "January", 2 : "February", 3 : "March",
58
4 : "April", 5 : "May", 6 : "June", 7 : "July",
59
8 : "August", 9 : "September", 10 : "October",
60
11 : "November" }
61 aDictionary[ 12 ] = "December"
# add item to dictionary
62
63 print "The raw dictionary data is:", aDictionary
64 print "\nThe entries in the dictionary are:"
65
66 for item in aDictionary.keys():
67
print "aDictionary[ ", item, " ] = ", aDictionary[ item ]
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The first item in the tuple is 1
The second item in the tuple is a
The third item in the tuple is 3.0
The first item in the tuple is 1
The second item in the tuple is a
The third item in the tuple is 3.0
Used the += statement on the tuple
The raw tuple data is: (1, 'a', 3.0, 4)
The items in the tuple are:
1 a 3.0 4
The raw list data is: [0, 2, 3, 5]
Added an item to the list using the += statement
The items in the list are:
0 2 3 5 4
The raw dictionary data is: {12: 'December', 11: 'November', 10: 'October', 9:
'September', 8: 'August', 7: 'July', 6: 'June', 5: 'May', 4: 'April', 3: 'March',
2: 'February', 1: 'January'}
The entries in the dictionary are:
aDictionary[ 12 ] = December
aDictionary[ 11 ] = November
aDictionary[ 10 ] = October
aDictionary[ 9 ] = September
aDictionary[ 8 ] = August
aDictionary[ 7 ] = July
aDictionary[ 6 ] = June
aDictionary[ 5 ] = May
aDictionary[ 4 ] = April
aDictionary[ 3 ] = March
aDictionary[ 2 ] = February
aDictionary[ 1 ] = January
 2004 Prentice Hall, Inc. All rights reserved.
35.3 Tuples, Lists and Dictionaries
Method
append( item )
count( item )
extend( newList )
index( item )
insert( index,
item )
pop( [index] )
Purpose
Inserts item at the end of the list.
Returns the number of occurrences of item in the list.
Inserts newList at the end of the list.
Returns the index of the first occurrence of item in the list.
If the element is not in the list, a ValueError exception
occurs. [Note: We discuss exceptions in Section 35.5]
Inserts item at position index.
Removes and returns the last element in the list. If
parameter index is specified, removes and returns the
element at position index.
remove( item )
Removes the first occurrence of item from the list. If item
is not in the list, a ValueError exception occurs.
reverse()
Reverses the items in the list.
sort( [function] ) Sorts the items in the list. Optional parameter function is a
comparison function that may be user defined.
Fig. 35.8 Python list methods.
 2004 Prentice Hall, Inc. All rights reserved.
35.3 Tuples, Lists and Dictionaries
Method
clear()
copy()
get( key [, falseValue] )
has_key( key )
items()
keys()
setdefault( key [,
falseValue] )
update( otherDictionary )
values()
Fig. 35.9 Dictionary methods.
 2004 Prentice Hall, Inc. All rights reserved.
Description
Deletes all items from the dictionary.
Creates a copy of the dictionary.
Returns the value associated with key. If key is not
in the dictionary and if falseValue is specified,
returns the specified value.
Returns 1 if key is in the dictionary; returns 0 if key
is not in the dictionary.
Returns a list of tuples that are key-value pairs.
Returns a list of keys in the dictionary.
Behaves similarly to method get. If key is not in
the dictionary and falseValue is specified, inserts
the key and the specified value into the dictionary.
Adds all the key-value pairs from otherDictionary
to the current dictionary.
Returns a list of values in the dictionary.
35.4 String Processing and Regular
Expressions
• Regular expression
– Used to search through strings, text files, databases, and so
on
• Regular-expression string
– Defines a pattern with which text data can be compared
 2004 Prentice Hall, Inc. All rights reserved.
1
# Fig. 35.10: fig35_10.py
2
# Program to illustrate use of strings
Outline
3
4
# simple string assignments
5
string1 = "This is a string."
6
print string1
fig35_10.py
(1 of 2)
7
8
string2 = "This is a second string."
9
print string2
10
11 # string concatenation
12 string3 = string1 + " " + string2
13 print string3
14
15 # using operators
16 string4 = '*'
17 print "String with an asterisk: " + string4
18 string4 *= 10
19 print "String with 10 asterisks: " + string4
20
21 # using quotes
22 print "This is a string with \"double quotes.\""
23 print 'This is another string with "double quotes."'
24 print 'This is a string with \'single quotes.\''
25 print "This is another string with 'single quotes.'"
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26 print """This string has "double quotes" and 'single quotes.'"""
27
28 # string formatting
Outline
29 name = raw_input( "Enter your name: " )
30 age = raw_input( "Enter your age: " )
31 print "Hello, %s, you are %s years old." % ( name, age )
fig35_10.py
(2 of 2)
This is a string.
This is a second string.
This is a string. This is a second string.
String with an asterisk: *
String with 10 asterisks: **********
This is a string with "double quotes."
This is another string with "double quotes."
This is a string with 'single quotes.'
This is another string with 'single quotes.'
This string has "double quotes" and 'single quotes.'
Enter your name: Brian
Enter your age: 33
Hello, Brian, you are 33 years old.
 2004 Prentice Hall, Inc.
All rights reserved.
35.4 String Processing and Regular
Expressions
Symbol
c
s
d
u
o
x
X
f
e, E
g, G
Fig. 35.11
Meaning
Single character (i.e., a string of length 1).
String.
Signed decimal integer.
Unsigned decimal integer.
Unsigned octal integer.
Unsigned hexadecimal integer (using format abcdef).
Unsigned hexadecimal integer (using format ABCDEF).
Floating-point number.
Floating-point number (using scientific notation).
Floating-point number (using least-significant digits).
String-format characters.
 2004 Prentice Hall, Inc. All rights reserved.
1
# Fig. 35.12: fig35_12.py
2
# Program searches a string using the regular expression module.
Outline
3
4
import re
5
6
searchString = "Testing pattern matches"
fig35_12.py
(1 of 2)
7
8
expression1 = re.compile( r"Test" )
9
expression2 = re.compile( r"^Test" )
10 expression3 = re.compile( r"Test$" )
11 expression4 = re.compile( r"\b\w*es\b" )
12 expression5 = re.compile( r"t[aeiou]", re.I )
13
14 if expression1.search( searchString ):
15
print '"Test" was found.'
16
17 if expression2.match( searchString ):
18
print '"Test" was found at the beginning of the line.'
19
20 if expression3.match( searchString ):
21
print '"Test" was found at the end of the line.'
22
23 result = expression4.findall( searchString )
24
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25 if result:
26
print 'There are %d words(s) ending in "es":' % \
( len( result ) ),
27
Outline
28
29
for item in result:
print " " + item,
30
fig35_12.py
(2 of 2)
31
32 print
33 result = expression5.findall( searchString )
34
35 if result:
36
print 'The letter t, followed by a vowel, occurs %d times:' % \
( len( result ) ),
37
38
39
for item in result:
40
print " " + item,
41
42 print
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35.4 String Processing and Regular
Expressions
Character
^
$
.
*
+
?
{m, n}
\b
\B
\d
\D
\w
[...]
[^...]
Fig. 35.13
Matches
Beginning of string.
End of string.
Any character, except a newline.
Zero or more occurrences of the pattern.
One or more occurrences of the preceding pattern.
Zero or one occurrence of the preceding pattern.
Between m and n occurrences of the preceding pattern.
Word boundary (i.e., the beginning or end of a word).
Nonword boundary.
Digit ([0–9]).
Nondigit.
Any alpha-numeric character.
Any character defined by the set.
Any character not defined by the set.
re module’s regular-expression characters.
 2004 Prentice Hall, Inc. All rights reserved.
35.5 Exception Handling
• Enables programs and programmers to identify an
error when it occurs and take appropriate action
• try…except blocks
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35.5 Exception Handling
Python 2.1 (#15, Apr 16 2001, 18:25:49) [MSC 32 bit
(Intel)] on win32
Type "copyright", "credits" or "license" for more
information.
>>> 1 / 0
Traceback (most recent call last):
File "<stdin>", line 1, in ?
ZeroDivisionError: integer division or modulo by zero
>>>
Fig. 35.14
Interactive session illustrating a ZeroDivisionError exception.
 2004 Prentice Hall, Inc. All rights reserved.
1
# Fig. 35.15: fig35_15.py
2
# A simple program that illustrates exceptions.
Outline
3
4
5
def getFloat():
return float( raw_input( "Enter a number: " ) )
6
7
fig35_15.py
(1 of 1)
number1 = number2 = None
8
9
10
while number1 == None:
try:
number1 = getFloat()
11
12
except ValueError:
print "Value entered was not a number"
13
14
15 while number2 == None:
16
try:
number2 = getFloat()
17
18
except ValueError:
print "Value entered was not a number"
19
20
21 try:
22
result = number1 / number2
23 except ZeroDivisionError:
24
print "Cannot divide by zero!"
25 else:
26
print "The result of division is: %f" % result
 2004 Prentice Hall, Inc.
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35.6 Introduction to CGI Programming
• Use Python on the Web
– cgi
• For access to XHTML forms
• Directive (pound-bang or Shebang)
– Provides server with location of Python executable
• cgi module
– Provides functionalities for writing CGI scripts
• environ data member
– Holds all environment variables
– Cookie
• To read and write cookies
– smtplib
• To manipulate SMTP messages
– urllib
• To manipulate Web data
– ftplib
• To perform client-side FTP tasks
 2004 Prentice Hall, Inc. All rights reserved.
1
#!c:\Python\python.exe
2
# Fig 35.16: fig35_16.py
3
# Program to display CGI environment variables
Outline
4
5
import os
6
import cgi
fig35_16.py
(1 of 2)
7
8
print "Content-type: text/html"
9
print
10
11 print """<!DOCTYPE html PUBLIC
12
"-//W3C//DTD XHTML 1.0 Transitional//EN"
13
"DTD/xhtml1-transitional.dtd">"""
14
15 print """
16 <html xmlns = "http://www.w3.org/1999/xhtml" xml:lang="en"
17
lang="en">
18
<head><title>Environment Variables</title></head>
19
<body><table style = "border: 0">"""
20
21 rowNumber = 0
22
23 for item in os.environ.keys():
24
rowNumber += 1
25
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26
27
28
29
if rowNumber % 2 == 0:
backgroundColor = "white"
else:
backgroundColor = "lightgrey"
30
31
print """<tr style = "background-color: %s">
32
<td>%s</td><td>%s</td></tr>""" \
33
% ( backgroundColor, item,
34
Outline
fig35_16.py
(2 of 2)
cgi.escape( os.environ[ item ] ) )
35
36 print """</table></body></html>"""
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35.7 Form Processing and Business Logic
• XHTML forms
– Allow users to enter data to be sent to a Web server for
processing
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1
<!DOCTYPE html PUBLIC
2
"-//W3C//DTD XHTML 1.0 Transitional//EN"
3
"DTD/xhtml1-transitional.dtd">
4
<!-- Fig. 35.17: fig35_17.html -->
5
6
7
8
9
Outline
<html xmlns = "http://www.w3.org/1999/xhtml" xml:lang="en"
fig35_17.html
(1 of 3)
lang="en">
<head>
<title>Sample FORM to take user input in HTML</title>
10 </head>
11
12 <body style = "font-family: Arial, sans-serif; font-size: 11pt">
13
14
15
16
17
<div style = "font-size: 15pt; font-weight: bold">
This is a sample registration form.
</div>
Please fill in all fields and click Register.
18
19
<form method = "post" action = "/cgi-bin/fig35_18.py">
20
<img src = "images/user.gif" alt = "user" /><br />
21
<div style = "color: blue">
22
23
Please fill out the fields below.<br />
</div>
24
25
<img src = "images/fname.gif" alt = "firstname" />
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26
<input type = "text" name = "firstname" /><br />
27
<img src = "images/lname.gif" alt = "lastname" />
28
<input type = "text" name = "lastname" /><br />
29
<img src = "images/email.gif" alt = "email" />
30
<input type = "text" name = "email" /><br />
31
<img src = "images/phone.gif" alt = "phone" />
32
<input type = "text" name = "phone" /><br />
Outline
fig35_17.html
(2 of 3)
33
34
35
36
<div style = "font-size: 8pt">
Must be in the form (555)555-5555<br/><br/>
</div>
37
38
<img src = "images/downloads.gif" alt = "downloads" /><br />
39
<div style = "color: blue">
40
41
Which book would you like information about?<br />
</div>
42
43
<select name = "book">
44
<option>XML How to Program</option>
45
<option>Python How to Program</option>
46
<option>E-business and E-commerce How to Program</option>
47
<option>Internet and WWW How to Program 3e</option>
48
<option>C++ How to Program 4e</option>
49
<option>Java How to Program 5e</option>
50
<option>Visual Basic How to Program</option>
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51
</select>
52
<br /><br />
Outline
53
54
<img src = "images/os.gif" alt = "os" /><br />
55
<div style = "color: blue">
56
Which operating system are you
57
currently using?<br />
58
fig35_17.html
(3 of 3)
</div>
59
60
<input type = "radio" name = "os" value = "Windows XP"
61
checked = "checked" />
62
Windows XP
63
<input type = "radio" name = "os" value = "Windows 2000" />
64
Windows 2000
65
<input type = "radio" name = "os" value = "Windows 95_98" />
66
Windows 95/98/ME<br />
67
<input type = "radio" name = "os" value = "Linux" />
68
Linux
69
<input type = "radio" name = "os" value = "Other" />
70
Other<br />
71
<input type = "submit" value = "Register" />
72
73
</form>
74 </body>
75 </html>
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1
#!c:\Python\python.exe
2
# Fig. 35.18: fig35_18.py
3
# Program to read information sent to the server from the
4
# form in the form.html document.
5
6
import cgi
7
import re
Outline
fig35_18.py
(1 of 4)
8
9
# the regular expression for matching most US phone numbers
10 telephoneExpression = \
11
re.compile( r'^\(\d{3}\)\d{3}-\d{4}$' )
12
13 def printContent():
14
print "Content-type: text/html"
15
print
16
print """
17 <html xmlns = "http://www.w3.org/1999/xhtml" xml:lang="en"
18
lang="en">
19
<head><title>Registration results</title></head>
20
<body>"""
21
22 def printReply():
23
print """
24
Hi <span style = "color: blue; font-weight: bold">
25
%(firstName)s</span>.
 2004 Prentice Hall, Inc.
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26
Thank you for completing the survey.<br />
27
You have been added to the <span style = "color: blue;
28
font-weight: bold">%(book)s </span> mailing list.<br /><br />
Outline
29
30
<span style = "font-weight: bold">
31
The following information has been saved in our database:
32
</span><br />
fig35_18.py
(2 of 4)
33
34
35
<table style = "border: 0; border-width: 0;
border-spacing: 10">
36
<tr><td style = "background-color: yellow">Name </td>
37
<td style = "background-color: yellow">Email</td>
38
<td style = "background-color: yellow">Phone</td>
39
<td style = "background-color: yellow">OS</td></tr>
40
41
42
43
<tr><td>%(firstName)s %(lastName)s</td><td>%(email)s</td>
<td>%(phone)s</td><td>%(os)s</td></tr>
</table>
44
45
<br /><br /><br />
46
47
<div style = "text-align: center; font-size: 8pt">
48
This is only a sample form.
49
You have not been added to a mailing list.
50
</div></center>
 2004 Prentice Hall, Inc.
All rights reserved.
51
""" % personInfo
Outline
52
53 def printPhoneError():
54
55
print """<span style = "color: red; font-size 15pt">
56
INVALID PHONE NUMBER</span><br />
57
A valid phone number must be in the form
58
<span style = "font-weight: bold">(555)555-5555</span>
59
<span style = "color: blue"> Click the Back button,
60
enter a valid phone number and resubmit.</span><br /><br />
61
Thank You."""
fig35_18.py
(3 of 4)
62
63 def printFormError():
64
65
print """<span style = "color: red; font-size 15pt">
66
FORM ERROR</span><br />
67
You have not filled in all fields.
68
<span style = "color: blue"> Click the Back button,
69
fill out the form and resubmit.</span><br /><br />
70
Thank You."""
71
72 printContent()
73
74 form = cgi.FieldStorage()
75
 2004 Prentice Hall, Inc.
All rights reserved.
76 try:
77
personInfo = { 'firstName' : form[ "firstname" ].value,
78
'lastName' : form[ "lastname" ].value,
79
'email' : form[ "email" ].value,
80
'phone' : form[ "phone" ].value,
81
'book' : form[ "book" ].value,
82
'os' : form[ "os" ].value }
Outline
fig35_18.py
(4 of 4)
83 except KeyError:
84
printFormError()
85
86 if telephoneExpression.match( personInfo[ 'phone' ] ):
87
printReply()
88 else:
89
printPhoneError()
 2004 Prentice Hall, Inc.
All rights reserved.
35.8 Cookies
• Small text files
– State information
•
•
•
•
Username
Password
Specific information helpful when user returns
Etc.
 2004 Prentice Hall, Inc. All rights reserved.
1
<!DOCTYPE html PUBLIC
2
"-//W3C//DTD XHTML 1.0 Transitional//EN"
3
"DTD/xhtml1-transitional.dtd">
4
<!-- Fig. 35.19: fig35_19.html -->
5
6
<html xmlns = "http://www.w3.org/1999/xhtml" xml:lang = "en"
7
lang = "en">
8
<head>
9
10
Outline
fig35_19.html
(1 of 2)
<title>Writing a cookie to the client computer</title>
</head>
11
12 <body style = "background-image: images/back.gif;
13
font-family: Arial,sans-serif; font-size: 11pt" >
14
15
16
17
<span style = "font-size: 15pt; font-weight: bold">
Click Write Cookie to save your cookie data.
</span><br />
18
19
<form method = "post" action = "/cgi-bin/fig35_20.py">
20
<span style = "font-weight: bold">Name:</span><br />
21
<input type = "text" name = "name" /><br />
22
<span style = "font-weight: bold">Height:</span><br />
23
<input type = "text" name = "height" /><br />
24
<span style = "font-weight: bold">Favorite Color</span><br />
25
<input type = "text" name = "color" /><br />
 2004 Prentice Hall, Inc.
All rights reserved.
26
27
<input type = "submit" value = "Write Cookie" />
</form>
Outline
28
29 </body>
30 </html>
fig35_19.html
(2 of 2)
 2004 Prentice Hall, Inc.
All rights reserved.
1
#!C:\Python\python.exe
2
# Fig. 35.20: fig35_20.py
3
# Writing a cookie to a client's machine
Outline
4
5
import cgi
6
import Cookie
7
import time
fig35_20.py
(1 of 3)
8
9
def printContent():
10
print "Content-type: text/html"
11
print
12
print """
13 <html xmlns = "http://www.w3.org/1999/xhtml" xml:lang="en"
14
lang="en">
15
<head><title>Cookie values</title></head>"""
16
17 form = cgi.FieldStorage()
# get form information
18
19 try:
# extract form values
20
name = form[ "name" ].value
21
height = form[ "height" ].value
22
color = form[ "color" ].value
23 except KeyError:
24
printContent()
25
print """<body><h3>You have not filled in all fields.
 2004 Prentice Hall, Inc.
All rights reserved.
26
<span style = "color: blue"> Click the Back button,
27
fill out the form and resubmit.<br /><br />
28
Thank You. </span></h3>"""
Outline
29 else:
30
31
# construct cookie expiration date and path
32
expirationFormat = "%A, %d-%b-%y %X %Z"
33
expirationTime = time.localtime( time.time() + 300 )
34
expirationDate = time.strftime( expirationFormat,
35
36
fig35_20.py
(2 of 3)
expirationTime )
path = "/"
37
38
# construct cookie contents
39
cookie = Cookie.SimpleCookie()
40
41
cookie[ "Name" ] = name
42
cookie[ "Name" ][ "expires" ] = expirationDate
43
cookie[ "Name" ][ "path" ] = path
44
45
cookie[ "Height" ] = height
46
cookie[ "Height" ][ "expires" ] = expirationDate
47
cookie[ "Height" ][ "path" ] = path
48
49
cookie[ "Color" ] = color
50
cookie[ "Color" ][ "expires" ] = expirationDate
 2004 Prentice Hall, Inc.
All rights reserved.
51
cookie[ "Color" ][ "path" ] = path
52
53
# print cookie to user and page to browser
54
print cookie
55
56
printContent()
57
print """<body style = "background-image: /images/back.gif;
58
font-family: Arial,sans-serif; font-size: 11pt">
59
The cookie has been set with the following data: <br /><br />
Outline
fig35_20.py
(3 of 3)
60
61
<span style = "color: blue">Name:</span> %s<br />
62
<span style = "color: blue">Height:</span> %s<br />
63
<span style = "color: blue">Favorite Color:</span>
64
<span style = "color: %s"> %s</span><br />""" \
65
% ( name, height, color, color )
66
67
print """<br /><a href= "fig35_21.py">
68
Read cookie values</a>"""
69
70 print """</body></html>"""
 2004 Prentice Hall, Inc.
All rights reserved.
 2004 Prentice Hall, Inc. All rights reserved.
1
#!C:\Python\python.exe
2
# Fig. 35.21: fig35_21.py
3
# Program that retrieves and displays client-side cookie values
Outline
4
5
import Cookie
6
import os
fig35_21.py
(1 of 2)
7
8
print "Content-type: text/html"
9
print
10 print """
11 <html xmlns = "http://www.w3.org/1999/xhtml" xml:lang="en"
12
lang="en">
13
<head><title>Cookie values</title></head>
14
<body style =
15
font-family: Arial, sans-serif; font-size: 11pt">"""
16
17 try:
18
cookie = Cookie.SimpleCookie()
19
cookie.load( os.environ[ "HTTP_COOKIE" ] )
20 except KeyError:
21
print """<span style = "font-weight: bold">Error reading cookies
22
</span>"""
23 else:
24
print """<span style = "font-weight: bold">
25
The following data is saved in a cookie on your computer.
 2004 Prentice Hall, Inc.
All rights reserved.
26
</span><br /><br />"""
27
28
29
print """<table style = "border-width: 5; border-spacing: 0;
padding: 10">"""
30
31
32
for item in cookie.keys():
fig35_21.py
(2 of 2)
print """<tr>
33
<td style = "background-color: lavender">%s</td>
34
<td style = "background-color: white">%s</td>
35
Outline
</tr>""" % ( item, cookie[ item ].value )
36
37
print """</table>"""
38
39 print """</body></html>"""
 2004 Prentice Hall, Inc.
All rights reserved.
35.9 Database Application Programming
Interface (DB-API)
• Python Database Special Interest Group (SIG)
– Formed to develop a specification for Python database
application programming interface (DB-API)
 2004 Prentice Hall, Inc. All rights reserved.
35.9.1 Setup
• MySQL and the MySQLdb module must be
installed
 2004 Prentice Hall, Inc. All rights reserved.
35.9.2 Simple DB-API Program
• Lets user choose an author from XHTML dropdown list
• User clicks button to query database
• Database query returns a list of all books by
author
 2004 Prentice Hall, Inc. All rights reserved.
1
#!c:\Python\python.exe
2
# Fig. 35.22: fig35_22.py
3
# A program to illustrate Python's database connectivity.
4
import MySQLdb
Outline
fig35_22.py
(1 of 2)
5
6
print "Content-type: text/html"
7
print
8
print """
9
<html xmlns = "http://www.w3.org/1999/xhtml" xml:lang="en"
10
lang="en">
11
<head><title>Select Author</title></head>
12
<body style =
13
font-family: Arial, sans-serif; font-size: 11pt">"""
14
15 try:
16
connection = MySQLdb.connect( db = "books" )
17 except OperationalError:
18
print "Unable to connect to database: %s" % message
19 else:
20
cursor = connection.cursor()
21
cursor.execute( "SELECT * FROM Authors" )
22
authorList = cursor.fetchall()
23
24
cursor.close()
# close cursor
25
connection.close()
# close connection
 2004 Prentice Hall, Inc.
All rights reserved.
26
27
print """
28
<form method = "post" action = "/cgi-bin/fig35_23.py">
29
<select name = "authorID">"""
fig35_22.py
(2 of 2)
30
31
32
Outline
for author in authorList:
print """<option value = %d>%s, %s</option>"""
\
% ( author[ 0 ], author[ 2 ], author[ 1 ] )
33
34
35
print """
36
</select>
37
<input type = "submit" value = "Execute Query" />
38
</ form>"""
39
40 print """</body></html>"""
 2004 Prentice Hall, Inc.
All rights reserved.
1
#!c:\Python\python.exe
2
# Fig. 35.23: fig35_23.py
3
# A program to illustrate Python's database connectivity.
Outline
4
5
import cgi
6
import MySQLdb
7
import sys
fig35_23.py
1 of 3
8
9
# get results from form
10 form = cgi.FieldStorage()
11
12 print "Content-type: text/html"
13 print
14 print """
15 <html xmlns = "http://www.w3.org/1999/xhtml" xml:lang="en"
16
lang="en">
17
<head><title>Query results</title></head>
18
<body style =
19
font-family: Arial, sans-serif; font-size: 11pt">"""
20
21 try:
22
authorID = form[ "authorID" ].value
23 except KeyError:
24
print """<span style = "color: red size = 15pt">
25
FORM ERROR</span><br />
 2004 Prentice Hall, Inc.
All rights reserved.
26
You did not select an author.<br />
27
<span style = "color: blue"> Click the Back button,
28
fill out the form and resubmit.<br /><br />
29
Thank You.</span></body></html>"""
30
sys.exit()
Outline
fig35_23.py
(2 of 3)
31
32 # connect to database and get cursor
33 try:
34
connection = MySQLdb.connect( db = 'books' )
35 except OperationalError:
36
print """<span style = "color: red size = 15pt">
37
DATABASE ERROR</span><br /> Unable to connect to database.
38
</body></html>"""
39
sys.exit()
40
41 queryString = """select Titles.* from Titles, AuthorISBN
42
where AuthorISBN.AuthorID=%s and
43
Titles.ISBN=AuthorISBN.ISBN""" % authorID
44
45 cursor = connection.cursor()
46 cursor.execute( queryString )
47
48 results = cursor.fetchall()
49
50 cursor.close()
# close cursor
 2004 Prentice Hall, Inc.
All rights reserved.
51 connection.close()
# close connection
52
53 # display results
Outline
54 print """<table style = "border: groove 2 pt;
55
56
border-colapse: separate">
<tr>
57
<th>ISBN</th>
58
<th>Title</th>
59
<th>Edition</th>
60
<th>Year</th>
61
<th>Description</th>
62
<th>Publisher ID</th>
63
fig35_23.py
(3 of 3)
</tr>"""
64
65 for row in results:
66
print "<tr>"
67
68
69
for entry in row:
print '<td style = "border: solid 2pt">%s</td>' % entry
70
71
print "</tr>"
72
73 print """</table></body></html>"""
 2004 Prentice Hall, Inc.
All rights reserved.
 2004 Prentice Hall, Inc. All rights reserved.
35.10 Operator Precedence Chart
Operator
Type
Associativity
' '
string conversion
left to right
{ }
[ ]
( )
( )
[ : ]
[ ]
.
**
~
+
*
/
%
Fig. 35.24
dictionary creation
list creation
tuple creation or expression grouping
function call
slicing
subscript access
member access
exponentiation
bitwise NOT
unary plus
unary minus
multiplication
division
modulus (remainder)
Python operator precedence chart.
 2004 Prentice Hall, Inc. All rights reserved.
left to right
left to right
left to right
left to right
left to right
left to right
left to right
right to left
left to right
right to left
left to right
35.10 Operator Precedence Chart
Operator
+
<<
>>
&
^
|
<
<=
>
>=
!=
==
Fig. 35.24
Type
addition
subtraction
left shift
right shift
bitwise AND
bitwise XOR
bitwise OR
less than
less than or equal
greater than
greater than or equal
not equal
equal
Python operator precedence chart.
 2004 Prentice Hall, Inc. All rights reserved.
Associativity
left to right
left to right
left to right
left to right
left to right
left to right
35.10 Operator Precedence Chart
Operator
Type
Associativity
is, is not
identity
left to right
in, not in
not
and
or
lambda
Fig. 35.24
membership tests
boolean NOT
boolean AND
boolean OR
lambda expressions (anonymous
functions)
Python operator precedence chart.
 2004 Prentice Hall, Inc. All rights reserved.
left to right
left to right
left to right
left to right
left to right
35.11 Web Resources
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
www.python.org
www.zope.com
www.zope.org
starship.python.net
www.python.org/download/download_mac.html
www.vex.net/parnassus
www.pythonware.com
starship.python.net/crew/davem/cgifaq/faqw.cgi
www.devshed.com/Server_Side/Python/CGI
starship.python.net/crew/aaron_watters/pws.html
www.python.org/doc/howto/regex/regex.html
www.python.org/windows/win32com
gadfly.sourceforge.net
aspn.activestate.com/ASPN/Python/Cookbook
www.python.org/windows/win32/odbc.html
starship.python.net/crew/bwilk/access.html
www.python.org/doc/Comparisons.html
www.vic.auug.org.au/auugvic/av_paper_python.html
www.networkcomputing.com/unixworld/tutorial/005/005.html
 2004 Prentice Hall, Inc. All rights reserved.