Day 23 反射

isinstance(obj,cls)检查是否obj是类cls的对象
class Foo(object):
    pass
obj = Foo()
print(isinstance(obj,Foo))

issubclass(sub,super)检查sub类是否是super的派生类
class Foo(object):
    pass

class Bar(Foo):
    pass

print(issubclass(Bar,Foo))

class Foo:
    role = ‘person‘
    def __init__(self,name,age):
        self.name = name
        self.age = age
    def func(self):
        print(‘hi,%s‘%self.name)

p = Foo(‘alex‘,26)

# 获取属性 getattr(object,name,default = None)
print(getattr(p,‘age‘)) #属性
print(getattr(p,‘func‘)) #方法
func = getattr(p,‘func‘)
func()

# 设置属性 setattr(x,y,z) sets the named attribute on the given object to the specified value
setattr(p,‘name‘,‘nero‘)
print(p.__dict__)
setattr(p,‘show_name‘,lambda self:self.name +‘sb‘)
print(p.show_name(p))

# 删除属性 delattr(x,y)   Deletes the named attribute from the given object.
delattr(p,‘age‘)
delattr(p,‘show_name‘)
delattr(p,‘show_name111‘) #报错

print(p.__dict__)

# 类也是对象
class Foo(object):
    staticField = ‘old boy‘

    def __init__(self):
        self.name = ‘wupeiqi‘

    def func(self):
        return ‘func‘

    @staticmethod
    def bar():
        return ‘bar‘

print(getattr(Foo,‘staticField‘))
print(getattr(Foo,‘func‘))
print(getattr(Foo,‘bar‘))

# 反射当成模块成员
import sys

def s1():
    print (s1)

def s2():
    print(s2)

this_module = sys.modules[__name__]

print(hasattr(this_module,‘s1‘))
print(getattr(this_module, ‘s2‘))

# 导入其他模块，利用反射查找该模块是否存在某个方法
‘‘‘
程序目录：
module_test.py
index.py

当前文件：
index.py
‘‘‘

import model_test as obj

print(hasattr(obj,‘test‘))
getattr(obj,‘test‘)

# __len__
class A:
    def __init(self):
        self.a =1
        self.b =2

    def __len__(self):
        return len(self.__dict__)

a= A()
print(len(a))

#__hash__
class A:
    def __init__(self):
        self.a = 1
        self.b = 2
    def __hash__(self):
        return hash(str(self.a)+str(self.b))

a = A()
print(hash(a))

class A:
    role = ‘person‘
    def func(self):
        print(‘*‘*self)
# ret = input(‘>>>‘)
# print(A.__dict__[ret])
print(getattr(A,‘role‘))    # 从A的命名空间里找一个属性 ，直接就可以找到这个属性的值
f = getattr(A,‘func‘);f(2) # 从A的命名空间里找一个方法 ，找到的是这个方法的内存地址
getattr(A,‘func‘)(2)
A.func(2)

默写1
class A:
    role = ‘Person‘
    def __init__(self):
        self.money = 500
    def func(self):
        print(‘*‘*10)

a = A()
print(a.func)
getattr(a,‘func‘)()
print(getattr(a,‘money‘))

默写2
def login():
    print(‘执行login功能‘)

def register():
    print(‘执行register功能‘)

import sys  # 和python解释器相关的内容都在sys里
print(sys.modules[‘__main__‘])
func = input(‘>>>‘)
if hasattr(sys.modules[‘__main__‘],func):
    getattr(sys.modules[‘__main__‘],func)()