类似的文章：
- Python编程：class类面向对象
- Python编程：面向对象深入
文章内容
面向对象 类， 对象
属性和方法
封装 数据隐藏
继承(object) 代码复用
多态 接口重用
magic method魔术方法
构造对象
运算符
类的展现
类的属性访问面向对象 类， 对象
构造函数 def __init__
析构函数 def __del__
新式类(object)和老式类属性访问控制 靠自觉
public name
protected _age
private __weight函数和方法(类)
public
protected
private
method
@classmethod
@property类继承
调用父类方法
super(superclass, self).method(args)
superClass.method(args)
isinstance
issubclass
多继承多态：继承 方法重写
magic method魔术方法
对象实例化：创建对象 -》初始化对象
__new__(cls)
__init__(self)
回收对象
__del__(self)
运算符
__cmp__(self, other)
__eq__(self, other)
__lt__(self, other)
__gt__(self, other)
__add__(self, other)
__sub__(self, other)
__mul__(self, other)
__div__(self, other)
__or__(self, other)
__and__(self, other)
转为字符串
__str__ -> 适合人看
__repr__ -> 适合机器看 -> eval()直接运行
__unicode__
__dir__
设置对象属性
def __setattr__(self, name, value)
self.__dict__[name] =value
错误设置，默认递归1000次
def __setattr__(self, name, value):
setattr(self, name, value)
查询对象属性
__getattr__(self, name) 没有被查询到调用
__getattribute__(self, name) 每次查询都会调用
删除对象属性
__delattr__(self, name)代码示例
类的继承
# -*- coding: utf-8 -*-
# 父类
class Person(object):
count = 0
# 新建对象
def __new__(cls, *args, **kwargs):
print("call __new__")
return super(Person, cls).__new__(cls, *args, **kwargs)
# 初始化
def __init__(self, name, age, weight):
print("call __init__")
self.name = name
self._age = age
self.__weight = weight
Person.count += 1
@classmethod
def get_count(cls):
return cls.count
@property
def weight(self):
return self.__weight
def say_hello(self):
print("hello")
# 子类
class EarthPerson(Person):
def __init__(self, name, age, weight, language):
super(EarthPerson, self).__init__(name, age, weight)
self.language = language
# 重写父类方法
def say_hello(self):
print("hello, my name is %s"%self.name)
def introduce(person):
if isinstance(person, Person):
person.say_hello()
if __name__ == '__main__':
p1 = Person("tom", 23, 60)
"""
call __new__
call __init__
"""
p2 = EarthPerson("jack", 24, 65, "English")
"""
call __new__
call __init__
"""
print(p1) # <__main__.Person object at 0x106fb2350>
print(p1.__dict__)
# {'_age': 23, 'name': 'tom', '_Person__weight': 60}
print(dir(p1))
"""
['_Person__weight', '__class__', '__delattr__', '__dict__',
'__doc__', '__format__', '__getattribute__', '__hash__',
'__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__',
'__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__',
'__weakref__', '_age', 'count', 'get_count', 'name', 'say_hello', 'weight']
"""
print(p1.name) # tom
print(p1._age) # 23
print(p1._Person__weight) # 60
print(p1.weight) # 60
print(Person.count) # 2
print(Person.get_count()) # 2
p1.say_hello() # hello
print(p2) # <__main__.EarthPerson object at 0x106fb2390>
print(issubclass(EarthPerson, Person)) # True
print(isinstance(p2, Person)) # True
p2.say_hello() # hello, my name is jack
introduce(p2) # hello, my name is jack
introduce(p1) # hello魔术方法
class Point(object):
def __init__(self, x, y):
self.x = x
self.y = y
def __eq__(self, other):
if isinstance(other, Point):
if self.x == other.x and self.y == other.y:
return True
else:
return False
else:
raise Exception("the type must be Ponit")
def __add__(self, other):
if isinstance(other, Point):
x = self.x + other.x
y = self.y + other.y
return Point(x, y)
else:
raise Exception("the type must be Ponit")
def __str__(self):
return "Ponit(x={x}, y={y})".format(x=self.x, y=self.y)
def __dir__(self):
return self.__dict__.keys()
def __getattribute__(self, name):
# return getattr(self, name) 错误
# return self.__dict__[name] 错误
return super(Point, self).__getattribute__(name)
def __setattr__(self, name, value):
# setattr(self, name, value) 错误
self.__dict__[name] = value
if __name__ == '__main__':
point1 = Point(1, 2)
point2 = Point(1, 2)
print(point1 == point2) # True
print(point1 + point2) # Ponit(x=2, y=4)
print(dir(point1)) # ['x', 'y']
