第七节

类的方法

1.静态方法

class Dog(object):
    def __init__(self,name):
        self.name = name

    @staticmethod
    def eat(self):
        print("%s is eating %s" % (self.name,"apple"))

    def talk(self):
        print("%s is talking"% self.name)

ainemo=Dog("tom")
ainemo.eat(ainemo)
ainemo.talk()
#只是名义上归类管理，实际上在静态方法里访问不了实例中的任何属性

显示结果：
tom is eating apple
tom is talking

2.类方法

class Dog(object):
    name = "jack"   #只有类变量才能在“类方法”中起作用
    def __init__(self,name):
        self.name = name    #实例变量不起作用

    @classmethod
    def eat(self):
        print("%s is eating %s" % (self.name,"apple"))

    def talk(self):
        print("%s is talking"% self.name)

d=Dog("tom")
d.eat()

#只能访问类变量，不能访问实例变量
显示结果：
jack is eating apple

3.属性方法

class Dog(object):
    def __init__(self,name):
        self.name = name
        self.__food = None

    @property   #attribute
    def eat(self):
        print("%s is eating %s" % (self.name,self.__food))

    @eat.setter
    def eat(self,food):
        print("food is %s" % food)
        #print("修改成功，%s is eating %s" % (self.name,food))
        self.__food = food

    @eat.deleter
    def eat(self):
        del self.__food
        print("删完了")

    def talk(self):
        print("%s is talking"% self.name)

d=Dog("tom")
d.eat
d.eat="banana"
d.eat
#del d.eat　　#会报错，因为将self.__food整个变量删除了
#d.eat   

#把一个方法变成一个静态属性
显示结果：
tom is eating None
food is banana
tom is eating banana

4.反射

1.hasattr

class Dog(object):
    def __init__(self,name):
        self.name = name

    def bulk(self):
        print("%s is yelling....." % self.name)

    def run(self):
        print("%s is running....." % self.name)

d = Dog("tom")
choice = input(">>:").strip()
print(hasattr(d,choice))

显示结果：
>>:run
True

2.getattr

class Dog(object):
    def __init__(self,name):
        self.name = name

    def bulk(self):
        print("%s is yelling....." % self.name)

    def run(self):
        print("%s is running....." % self.name)

d = Dog("tom")
choice = input(">>:").strip()
# print(hasattr(d,choice))
#
print(getattr(d,choice))
getattr(d,choice)()

显示结果：
>>:run
<bound method Dog.run of <__main__.Dog object at 0x000000B2BFDC98D0>>
tom is running.....

3.setattr

def eat(self):
    print("%s is eating....." %self.name)

class Dog(object):
    def __init__(self,name):
        self.name = name

    def bulk(self):
        print("%s is yelling....." % self.name)

    def run(self):
        print("%s is running....." % self.name)

d = Dog("tom")
choice = input(">>:").strip()
# print(hasattr(d,choice))
#
# print(getattr(d,choice))
# getattr(d,choice)()

if hasattr(d,choice):
    # attr = getattr(d,choice)
    setattr(d,choice,"jack")
    print(getattr(d,choice))
else:
    setattr(d,choice,eat)
    print(getattr(d,choice))
    d.eat(d)

显示结果：
>>:eat
<function eat at 0x000000C37E183E18>
tom is eating....

动态倒入模块

importlib

新建lib目录，边界aa.py
class C(object):
    def __init__(self):
        self.name = "panjitao"
切换到lib同级目录，新建test.py
import importlib

aa = importlib.import_module("lib.aa")
print(aa.C().name)

执行结果：
panjitao

断言

assert

#断言成功
import importlib

aa = importlib.import_module("lib.aa")

obj = aa.C().name
assert type(obj) is str
print("obj is str!")

显示结果：
obj is str!

#断言失败
import importlib

aa = importlib.import_module("lib.aa")
obj = aa.C().name

assert type(obj) is int
print("obj is int!")
显示结果：
Traceback (most recent call last):
  File "D:/Program Files/python-code/s12/day07/动态倒入模块.py", line 10, in <module>
    assert type(obj) is int
AssertionError