Python基础day-22[面向对象:反射,其他命令参数]

class A:
    name = ‘abc‘
    age = 19

#类的使用
print(hasattr(A,‘n1me‘))   #判断类是否含有某个属性   hasattr(类或者对象名,属性名)
print(getattr(A,‘name‘))   #获取对应属性的属性值    getattr(类或者对象名,属性名,出错返回的内容)  <----出错返回内容如果不写的话,当获取一个不存在的属性会报错,写了就会返回写的内容  
setattr(A,‘name‘,‘aaa‘)　　#设置属性的属性值　　　　setattr(类或者对象名,属性名,属性值)
print(A.name)
print(A.__dict__)
delattr(A,‘name‘)     #删除属性　　　　delattr(类或者对象名,属性名)
print(A.__dict__)

#对象的使用
p1 = A()   #实例化对象,下方使用方法同上
print(hasattr(p1,‘age‘))
print(getattr(p1,‘age‘))
setattr(p1,‘age‘,20)
print(p1.age)
delattr(p1,‘age‘)
print(p1.__dict__)

执行结果:
D:\Python\Python36-32\python.exe E:/Python/DAY-22/练习.py
False
abc
aaa
{‘__module__‘: ‘__main__‘, ‘name‘: ‘aaa‘, ‘age‘: 19, ‘__dict__‘: <attribute ‘__dict__‘ of ‘A‘ objects>, ‘__weakref__‘: <attribute ‘__weakref__‘ of ‘A‘ objects>, ‘__doc__‘: None}
{‘__module__‘: ‘__main__‘, ‘age‘: 19, ‘__dict__‘: <attribute ‘__dict__‘ of ‘A‘ objects>, ‘__weakref__‘: <attribute ‘__weakref__‘ of ‘A‘ objects>, ‘__doc__‘: None}
True
19
20
{}

Process finished with exit code 0

class Peolple:
    def __init__(self,name,age,sex):
        self.name = name
        self.age = age
        self.sex = sex

    def __str__(self):
        return ‘Name%s\nAge:%s\nSex:%s‘%(self.name,self.age,self.sex)  #定义信息返回格式

a = Peolple(‘abc‘,18,‘male‘)

print(a)   

执行结果:
D:\Python\Python36-32\python.exe E:/Python/DAY-22/练习.py
Nameabc
Age:18
Sex:male

Process finished with exit code 0

class Peolple:
    def __init__(self,name,age,sex):
        self.name = name
        self.age = age
        self.sex = sex

    def __str__(self):
        return ‘Name:%s\nAge:%s\nSex:%s‘%(self.name,self.age,self.sex)

    def __del__(self):
        print(‘%s is del‘%self.name)

a = Peolple(‘abc‘,18,‘male‘)
del a      #对象 a 被删除,触发__del__
print(‘----------main program--------------‘)

执行结果:
D:\Python\Python36-32\python.exe E:/Python/DAY-22/练习.py
abc is del
----------main program--------------

Process finished with exit code 0


换一下:
class Peolple:
    def __init__(self,name,age,sex):
        self.name = name
        self.age = age
        self.sex = sex

    def __str__(self):
        return ‘Name:%s\nAge:%s\nSex:%s‘%(self.name,self.age,self.sex)

    def __del__(self):
        print(‘%s is del‘%self.name)

a = Peolple(‘abc‘,18,‘male‘)
print(‘----------main program--------------‘)   #程序执行完毕后,清理 a对象时触发__del__

执行结果:
D:\Python\Python36-32\python.exe E:/Python/DAY-22/练习.py
----------main program--------------
abc is del

Process finished with exit code 0

class Peolple:
    def __init__(self,name,age,sex):
        self.name = name
        self.age = age
        self.sex = sex

    def __getitem__(self, item):   #查询属性
        return getattr(self, item)
    def __setitem__(self, key, value):  #设置属性
        setattr(self,key,value)
    def __delitem__(self, key):  #删除属性
        delattr(self,key)

a = Peolple(‘abc‘,18,‘male‘)  #实例化对象
print(a[‘name‘])   #获取name的属性值
 
a[‘name‘] = ‘a‘   #设置name的属性值
print(a[‘name‘])

del a[‘name‘]   #删除name 属性
print(a.__dict__)

执行结果:
D:\Python\Python36-32\python.exe E:/Python/DAY-22/练习.py
abc
a
{‘age‘: 18, ‘sex‘: ‘male‘}

Process finished with exit code 0