详解详细介绍l了Python类的继承

来源：动视网责编：小采时间：2020-11-27 14:24:55

详解详细介绍l了Python类的继承

详解详细介绍l了Python类的继承:Python类的继承(进阶5)1. python中什么是继承python中什么是继承:新类不必从头编写新类从现有的类继承，就自动拥有了现有类的所有功能新类只需要编写现有类缺少的新功能继承的好处：复用已有代码自动拥有了现有类的所有功能只需要编写缺少的新功能继承的特点

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导读详解详细介绍l了Python类的继承:Python类的继承(进阶5)1. python中什么是继承python中什么是继承:新类不必从头编写新类从现有的类继承，就自动拥有了现有类的所有功能新类只需要编写现有类缺少的新功能继承的好处：复用已有代码自动拥有了现有类的所有功能只需要编写缺少的新功能继承的特点

Python类的继承(进阶5)

1. python中什么是继承

python中什么是继承:

新类不必从头编写

新类从现有的类继承，就自动拥有了现有类的所有功能

新类只需要编写现有类缺少的新功能

继承的好处：

复用已有代码

自动拥有了现有类的所有功能

只需要编写缺少的新功能

继承的特点：

子类和父类是is关系

python继承的特点：

总是从某个类继承

不要忘记调用super().init

2. python中继承一个类

class Person(object):
 def init(self, name, gender):
 self.name = name
 self.gender = gender
class Teacher(Person):
 def init(self, name, gender, course):
 super(Teacher, self).init(name, gender)
 self.course = course

t = Teacher('Alice', 'Female', 'English')
print t.name
print t.course

3. python中判断类型

函数isinstance()可以判断一个变量的类型，既可以用在Python内置的数据类型如str、list、dict，也可以用在我们自定义的类，它们本质上都是数据类型。

class Person(object):
 def init(self, name, gender):
 self.name = name
 self.gender = gender

class Student(Person):
 def init(self, name, gender, score):
 super(Student, self).init(name, gender)
 self.score = score

class Teacher(Person):
 def init(self, name, gender, course):
 super(Teacher, self).init(name, gender)
 self.course = course

t = Teacher('Alice', 'Female', 'English')

print isinstance(t, Person)
print isinstance(t, Student)
print isinstance(t, Teacher)
print isinstance(t, object)

4. python中多态

class Person(object):
 def init(self, name, gender):
 self.name = name
 self.gender = gender
 def whoAmI(self):
 return 'I am a Person, my name is %s' % self.name

class Student(Person):
 def init(self, name, gender, score):
 super(Student, self).init(name, gender)
 self.score = score
 def whoAmI(self):
 return 'I am a Student, my name is %s' % self.name

class Teacher(Person):
 def init(self, name, gender, course):
 super(Teacher, self).init(name, gender)
 self.course = course
 def whoAmI(self):
 return 'I am a Teacher, my name is %s' % self.name
 
 
import json

class Students(object):
 def read(self):
 return r'["Tim", "Bob", "Alice"]'

s = Students()

print json.load(s)

5. python中多重继承

除了从一个父类继承外，Python允许从多个父类继承，称为多重继承。Java不能多继承

class A(object):
 def init(self, a):
 print 'init A...'
 self.a = a

class B(A):
 def init(self, a):
 super(B, self).init(a)
 print 'init B...'

class C(A):
 def init(self, a):
 super(C, self).init(a)
 print 'init C...'

class D(B, C):
 def init(self, a):
 super(D, self).init(a)
 print 'init D...'
 
 
class Person(object):
 pass

class Student(Person):
 pass

class Teacher(Person):
 pass

class SkillMixin(object):
 pass

class BasketballMixin(SkillMixin):
 def skill(self):
 return 'basketball'

class FootballMixin(SkillMixin):
 def skill(self):
 return 'football'

class BStudent(BasketballMixin):
 pass

class FTeacher(FootballMixin):
 pass

s = BStudent()
print s.skill()

t = FTeacher()
print t.skill()

6. python中获取对象信息

除了用 isinstance() 判断它是否是某种类型的实例外，还有没有别的方法获取到更多的信息呢？

首先可以用 type() 函数获取变量的类型，它返回一个 Type 对象

dir() 函数获取变量的所有属性

dir()返回的属性是字符串列表，如果已知一个属性名称，要获取或者设置对象的属性，就需要用 getattr() 和 setattr( )函数了

class Person(object):
 def init(self, name, gender):
 self.name = name
 self.gender = gender

class Student(Person):
 def init(self, name, gender, score):
 super(Student, self).init(name, gender)
 self.score = score
 def whoAmI(self):
 return 'I am a Student, my name is %s' % self.name

print type(123) # <type 'int'>

s = Student('Bob', 'Male', 88)
print s # <class 'main.Student'>

print dir(123) # ['abs', 'add', 'and', 'class', 'cmp', 'coerce', 'delattr', 'p', 'pmod', 'doc', 'float', 'floorp', 'format', 'getattribute', 'getnewargs', 'hash', 'hex', 'index', 'init', 'int', 'invert', 'long', 'lshift', 'mod', 'mul', 'neg', 'new', 'nonzero', 'oct', 'or', 'pos', 'pow', 'radd', 'rand', 'rp', 'rpmod', 'reduce', 'reduce_ex', 'repr', 'rfloorp', 'rlshift', 'rmod', 'rmul', 'ror', 'rpow', 'rrshift', 'rshift', 'rsub', 'rtruep', 'rxor', 'setattr', 'sizeof', 'str', 'sub', 'subclasshook', 'truep', 'trunc', 'xor', 'bit_length', 'conjugate', 'denominator', 'imag', 'numerator', 'real']

print dir(s) # ['class', 'delattr', 'dict', 'doc', 'format', 'getattribute', 'hash', 'init', 'module', 'new', 'reduce', 'reduce_ex', 'repr', 'setattr', 'sizeof', 'str', 'subclasshook', 'weakref', 'gender', 'name', 'score', 'whoAmI']

print getattr(s, 'name') # Bob
setattr(s, 'name', 'Adam') 
print s.name # Adam

class Person(object):

 def init(self, name, gender, **kw):
 self.name = name
 self.gender = gender
 for k, v in kw.iteritems():
 setattr(self, k, v)


p = Person('Bob', 'Male', age=18, course='Python')
print p.age # 18
print p.course #Python