第11章 面向对象的编程

longingo

例11.1 创建一个类
#!/usr/bin/python
# Filename: simplestclass.py
class Person:
    pass # An empty block
p = Person()
print p
例11.2 使用对象的方法
#!/usr/bin/python
# Filename: method.py
class Person:
    def sayHi(self):
        print 'Hello, how are you?'
p = Person()
p.sayHi()
# This short example can also be written as Person().sayHi()
例11.3 使用__init__方法
#!/usr/bin/python
# Filename: class_init.py
class Person:
    def __init__(self, name):
        self.name = name
    def sayHi(self):
        print 'Hello, my name is', self.name
p = Person('Swaroop')
p.sayHi()
# This short example can also be written as Person('Swaroop').sayHi()

例11.4 使用类与对象的变量
#!/usr/bin/python
# Filename: objvar.py
class Person:
    '''Represents a person.'''
    population = 0
    def __init__(self, name):
        '''Initializes the person's data.'''
        self.name = name
        print '(Initializing %s)' % self.name
        # When this person is created, he/she
        # adds to the population
        Person.population += 1
    def __del__(self):
        '''I am dying.'''
        print '%s says bye.' % self.name
        Person.population -= 1
        if Person.population == 0:
            print 'I am the last one.'
        else:
            print 'There are still %d people left.' % Person.population
    def sayHi(self):
        '''Greeting by the person.
        Really, that's all it does.'''
        print 'Hi, my name is %s.' % self.name
    def howMany(self):
        '''Prints the current population.'''
        if Person.population == 1:
            print 'I am the only person here.'
        else:
            print 'We have %d persons here.' % Person.population
swaroop = Person('Swaroop')
swaroop.sayHi()
swaroop.howMany()
kalam = Person('Abdul Kalam')
kalam.sayHi()
kalam.howMany()
swaroop.sayHi()
swaroop.howMany()
例11.5 使用继承
#!/usr/bin/python
# Filename: inherit.py
class SchoolMember:
    '''Represents any school member.'''
    def __init__(self, name, age):
        self.name = name
        self.age = age
        print '(Initialized SchoolMember: %s)' % self.name
    def tell(self):
        '''Tell my details.'''
        print 'Name:"%s" Age:"%s"' % (self.name, self.age),
class Teacher(SchoolMember):
    '''Represents a teacher.'''
    def __init__(self, name, age, salary):
        SchoolMember.__init__(self, name, age)
        self.salary = salary
        print '(Initialized Teacher: %s)' % self.name
    def tell(self):
        SchoolMember.tell(self)
        print 'Salary: "%d"' % self.salary
class Student(SchoolMember):
    '''Represents a student.'''
    def __init__(self, name, age, marks):
        SchoolMember.__init__(self, name, age)
        self.marks = marks
        print '(Initialized Student: %s)' % self.name
    def tell(self):
        SchoolMember.tell(self)
        print 'Marks: "%d"' % self.marks
t = Teacher('Mrs. Shrividya', 40, 30000)
s = Student('Swaroop', 22, 75)
print # prints a blank line
members = [t, s]
for member in members:
    member.tell() # works for both Teachers and Students



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