Python类成员方法
#coding:utf-8 ''' 1. 类;是一个模板,模板中包含了多个“函数” 2.对象;根据模板创建的实例(就是对象)。实例即是对象中的函数 类的成员: 类成员可以分为三大类: 1.实例属性(__init__()初始化实例里面的变量) 2.类属性(类里面的变量,初始化类的时候会一起加载到内存) 3.方法(类里面的函数) '''
#类方法(@classmethod): ''' 说明 1.类方法不能通过实例调用 2.类方法只能通过类来调用 3.类方法不能访问实例变量 ''' class Animal(object): hobbie = "meat" def __init__(self,name): self.name = name @classmethod #定义方法talk为类方法 def talk(self): print("%s is talking..."%self.hobbie) #实例调用类方法报错 #d = Animal("Eric") #d.talk() #AttributeError: type object 'Animal' has no attribute 'name' #类调用类方法 Animal.talk() #meat is talking...
#静态方法(@staticmethod): ''' 说明 1.当把方法变为静态方法后,这个方法跟实例就没关系了 2.在静态方法内,不能访问类变量和实例变量 ''' class Animal(object): hobbie = "meat" def __init__(self,name): self.name = name @staticmethod #定义talk为静态方法 # def talk(self): # print("%s is talking...",self.name) #尝试访问实例变量,但是报错 #TypeError: talk() missing 1 required positional argument: 'self' def talk(): print("is talking...") #is talking... #不访问实例变量和类变量,则正常 #调用talk静态方法 d = Animal("Eric") d.talk()
#把方法变成属性(@property ): ''' 说明 1.@property可以把方法转换成类属性 2.调用@property方法,也只能当做类属性来调用(不能加"()"调用) 作用: @property方法;可以当做一个公共区域,给所有人调用 ''' class Animal(object): hobbie = "meat" def __init__(self,name): self.name = name @property #定义habit方法为属性 def habit(self): print("%s habit is haha..."%self.name) @property def total_players(self): return 3 #调用habit方法报错(因habit方法以及被@property转换成属性了) # d = Animal("Eric") # d.habit() #TypeError: 'NoneType' object is not callable #把hobit当作属性调用 d = Animal("Eric") d.habit #Eric habit is haha... print(d.total_players) ''' 问题: 1.用@property把方法转换为属性后,怎么传参呢? 可通过(@方法名.setter)这个装饰器,重写该方法后即可传参 ''' class Animal(object): hobbie = "meat" def __init__(self,name): self.name = name self.num = None @property def total_players(self): return self.num @total_players.setter #通过.setter装饰器重写方法后,即可传值 def total_players(self,num): self.num = num print("total players:",self.num) d = Animal("Eric") #d.total_players(4) #这样传参显然不行了 print(d.total_players) #None d.total_players = 4 #传值,num等于4 print(d.total_players) #4 ''' 问题: 1.如果要删除用@property定义的方法呢? 可通过(@方法名.deleter)删除转换的方法属性 ''' class Animal(object): hobbie = "meat" def __init__(self,name): self.name = name self.num = None @property def total_players(self): return self.num @total_players.setter def total_players(self,num): self.num = num print("total players:",self.num) @total_players.deleter #删除total_players这个属性 def total_players(self): print("total players go delted.") del self.num #删除属性里面的某项内容 d = Animal("Eric") print(d.total_players) d.total_players = 4 del d.total_players #删除d.total_players print(d.total_players)