第十四天学习python

一些相关的BIF
issubclass(class,classinfo)

class a:
    pass
class b(a):
    pass
print(issubclass(b,a))
print(issubclass(a,b))

输出为
True
False

意思是b类在a类里面

isinstant(object,classinfo)

class a:
    pass
class b(a):
    pass
b1=b()
print(isinstance(b1,b))
print(isinstance(b1,a))
输出为
True
True

hasattr(object,name)

class c:
    def __init__(self,x=0):
        self.x=x
c1=c()
print(hasattr(c1,'x'))

getattr

class c:
    def __init__(self,x=0):
        self.x=x
c1=c()
print(hasattr(c1,'x'))
print(getattr(c1,'x'))
print(getattr(c1,'y','不存在'))
输出为
True
0
不存在

setattr

class c:
    def __init__(self,x=0):
        self.x=x
c1=c()
print(hasattr(c1,'x'))
print(getattr(c1,'x'))
print(getattr(c1,'y','不存在'))
setattr(c1,'y','haha')
print(getattr(c1,'y','不存在'))
输出为

True
0
不存在
haha

delatter

class c:
    def __init__(self,x=0):
        self.x=x
c1=c()
print(hasattr(c1,'x'))
print(getattr(c1,'x'))
print(getattr(c1,'y','不存在'))
setattr(c1,'y','haha')
print(getattr(c1,'y','不存在'))
delattr(c1,'y')
print(getattr(c1,'y','不存在'))
输出为
True
0
不存在
haha
不存在