面向对象的继承
面向对象三大特征
继承
# 面向对象三大特征: 封装 继承 多态
什么是继承?
继承就是新建类的一种方式,新建的类我们称为 子类 或者叫派生类，被继承的类我们称为父类或者基类
子类可以使用父类中的属性或者方法
为什么要用继承?
类解决了对象与对象之间的代码冗余问题
继承解决的是类与类之间的代码冗余问题
如何使用继承?
新式类：继承了object类的子子孙孙类都是新式类
经典类：没有继承object类的子子孙孙类都是经典类
# 新式类再经典类只有再python2中区分
#pzcharm 都是新式类
类的继承
# 父类
class Parent1:
pass
# 父类
class Parent2:
pass
# (类名) 括号中添加类名,那么这个函数将成为括号内的子类,反之,括号类的类名将是父类
# 子类
class Sub1(Parent1):
pass
# 子类
class Sub2(Parent1, Parent2):
pass
# __bases__ 查看Sub1所有继承的类
print(Sub1.__bases__) # (<class '__main__.Parent1'>,)
print(Sub2.__bases__) # (<class '__main__.Parent1'>, <class '__main__.Parent2'>)
# 使用__bases__查看父类
print(Parent1.__bases__) # (<class 'object'>,)
print(Parent2.__bases__) # (<class 'object'>,)
"""
说明父类默认继承object类,这是一个内置的类
变现形式class Parent1(object)
"""
类的继承实战举例1)
# 学生类
class Student():
school = 'SH'
def __init__(self,name,age,gender, course=None):
if course is None:
course = []
self.name = name
self.age = age
self.gender = gender
self.course = []
def choose_course(self,course):
self.course.append(course)
print('%s 选课成功 %s' % (self.name, self.course))
# 教师类
class Teacher():
school = 'SH'
def __init__(self,name,age,gender, level):
self.name = name
self.age = age
self.gender = gender
self.level = level
def score(self,stu_obj, score):
stu_obj.score = score
print('%s 给 %s 打了 %s 分' % (self.name, stu_obj.name, score))
# 学生类和教师类中有 school name age gender都需要使用的属性,那么,就可以创建一个父类,将二者都需要使用的放到公共类中
类的继承实战举例2)
# 父类，学生和教师都需要使用的类
class People():
school = 'SH'
def __init__(self, name, age, gender):
self.name = name
self.age = age
self.gender = gender
# 学生类
class Student(People):
def __init__(self, name, age, gender, course=None):
if course is None:
course = []
People.__init__(self, name, age, gender)
self.course = course
def choose_course(self, course):
self.course.append(course)
print('%s 选课成功 %s' % (self.name, self.course))
# 教师类
class Teacher(People):
def __init__(self, name, age, gender, level):
self.level = level
People.__init__(self, name, age, gender)
def score(self, stu_obj, score):
stu_obj.score = score
print('%s 给 %s 打了 %s 分' % (self.name, stu_obj.name, score))
s1 = Student('junjie', 18, 'nan', 'python')
print(s1.course)
t1 = Teacher('junjie', 19, 'nv', 5)
print(t1.level)
单继承下属性的查找
class Foo:
def f1(self):
print('Foo.f1')
def f2(self):
#
print('Foo.f2')
self.f1()
class Bar(Foo):
def f1(self):
print('Bar.f1')
obj = Bar() # {}
obj.f2()
# Foo.f2，Bar.f1
# 练习
class Foo:
def __f1(self): # _Foo__f1()
print('Foo.f1')
def f2(self):
#
print('Foo.f2')
self.__f1() # _Foo__f1()
class Bar(Foo):
def __f1(self): # # _Bar__f1()
print('Bar.f1')
obj = Bar() # {}
obj.f2()
# Foo.f2， Foo.f1
# 现在Bar的名称空间中寻找f2(),没有，由于Bar是Foo的子类找到f2输出Foo.f2,self谁调用就是谁,接着打印__f1的内容
Super（）和mro（）
class People():
school = 'SH'
def __init__(self, name, age, gender):
self.name = name
self.age = age
self.gender = gender
class gogo():
wazi = 'heisi'
def __init__(self):
print('我的')
# 学生类
class Student(People,gogo):
def __init__(self, name, age, gender,course=None):
if course is None:
course = []
# 使用super()会得到一个特殊的对象,该对象专门用来引用父类的属性,且严格按照MRO规定的顺序先后查找
super(Student, self).__init__(name, age, gender)
self.course = course
# gogo.__init__(self)
def get_go(self):
print('我%s 今年%s %s %s %s' % (self.name, self.age,self.gender,self.wazi,self.school))
s = Student('junjie',18,'喜欢')
print(s.wazi) # heisi
s.get_go() # 我junjie 今年18 喜欢 heisi SH
print(Student.mro()) # [<class '__main__.Student'>, <class '__main__.People'>, <class '__main__.gogo'>, <class 'object'>]
溜了溜了
