class Animal:pass #empty block

class Person:Count = 0def __init__(self, name, age):Person.Count += 1self.name = nameself.__age = agep = Person("peter", 25)
p1 = Person("john", 20)print Person.Count #2
print p.name #peter
print p.__age #AttributeError: Person instance has no attribute '__age'

 1 class SchoolMember:
 2     '''Represent any school member.'''
 3     def __init__(self, name, age):
 4         self.name = name
 5         self.age = age
 6         print "Initializing a school member."
 7
 8     def tell(self):
 9         '''Tell my details'''
10         print "Name: %s, Age: %s, " % (self.name, self.age),
11
12 class Teacher(SchoolMember):
13     '''Represent a teacher.'''
14     def __init__(self, name, age, salary):
15         SchoolMember.__init__(self, name, age)
16         self.salary = salary
17         print "Initializing a teacher"
18
19     def tell(self):
20         SchoolMember.tell(self)
21         print "Salary: %d" % self.salary
22
23 class Student(SchoolMember):
24     '''Represent a student.'''
25     def __init__(self, name, age, marks):
26         SchoolMember.__init__(self, name, age)
27         self.marks = marks
28         print "Initializing a student"
29
30     def tell(self):
31         SchoolMember.tell(self)
32         print "Marks: %d" % self.marks
33
34 print SchoolMember.__doc__
35 print Teacher.__doc__
36 print Student.__doc__
37
38 t = Teacher("Mr. Li", 30, 9000)
39 s = Student("Peter", 25, 90)
40
41 members = [t, s]
42
43 for m in members:
44     m.tell()

Represent any school member.
Represent a teacher.
Represent a student.
Initializing a school member.
Initializing a teacher
Initializing a school member.
Initializing a student
Name: Mr. Li, Age: 30,  Salary: 9000
Name: Peter, Age: 25,  Marks: 90

 1 test = '''\
 2 This is a program about file I/O.
 3
 4 Author: Peter Zhange
 5 Date: 2011/12/25
 6 '''
 7
 8 f = file("test.txt", "w") # open for writing, the file will be created if the file doesn't exist
 9 f.write(test) # write text to file
10 f.close() # close the file
11
12 f = file("test.txt") # if no mode is specified, the default mode is readonly.
13
14 while True:
15     line = f.readline()
16     if len(line) == 0:  # zero length indicates the EOF of the file
17         break
18     print line,
19
20 f.close()

import cPickledatafile = "data.data"namelist = ["peter", "john", "king"]f = file(datafile, "w")
cPickle.dump(namelist, f)
f.close()del namelistf = file(datafile)
storednamelist = cPickle.load(f)print storednamelist
#['peter', 'john', 'king']

try:print 1/0
except ZeroDivisionError, e:print e
except:print "error or exception occurred."#integer division or modulo by zero

class ShortInputException(Exception):'''A user-defined exception class'''def __init__(self, length, atleast):Exception.__init__(self)self.length = lengthself.atleast = atleasttry:s = raw_input("enter someting-->")if len(s) < 3:raise ShortInputException(len(s), 3)
except EOFError:print "why you input an EOF?"
except ShortInputException, ex:print "The lenght of input is %d, was expecting at the least %d" % (ex.length, ex.atleast)
else:print "no exception"
#The lenght of input is 1, was expecting at the least 3

try:f = file("test.txt")while True:line = f.readline()if len(line) == 0:breaktime.sleep(2)print line,
finally:f.close()print "Cleaning up..."