Python3.x基础学习-类--类的常用函数

issubclass()

issubclass()检测一个类是否是另外一个类的子类
格式1：issubclass(被检测类，父类)
返回值：布尔值 格式 1：issubclass(被检测类，(父类1，父类2，父类3...))
返回值：布尔值
注意：只要有一个类是当前被检测的父类，那么最终结果就是True

class A:
    pass
class B(A):
    pass
class C(B):
    pass

print(issubclass(C,A))
print(issubclass(C,A)) # 隔代继承也是子类

# True
# True

 

 

isinstance(对象，类)

class A:
    pass

class B(A):
    pass

class C(B):
    pass

c = C()
b = B()
a = A()

print(isinstance(c,C))
print(isinstance(c,A))
print(isinstance(a,(B,A)))

# True
# True
# True

 

反射方法

python 面向对象中的反射，通过字符串的形式操作对象相关的属性 python中的一切事物都是对象（都可以使用反射）
四个反射相关的函数
-hasattr:判断是否有此变量，返回bool值
-getattr:获取属性值或者获取方法变量的地址
-setattr:给类或者对象设置属性或者方法 （用的场合很少，了解即可）
-delattr:删除类或对象的属性或方法(用的场合很少，了解即可)
-反射类的属性和方法-反射对象的属性和方法 - 反射模块的属性和方法

getattr()获取对象/类中的成员值
格式3：getattr(对象，'属性名'[成员不存在时的默认值])
返回值：成员的值

class Teacher:
    dic = {'学生信息':'show_student','讲师信息':'show_teacher'}
    def __init__(self,name,age):
        self.name = name
        self.age = age

    @classmethod
    def func(cls):
        print("--func--")

    def show_student(self):
        print("--show student--")

    def show_teacher(self):
        print("--show teacher--")

print(getattr(Teacher,'dic'))
ret = getattr(Teacher,'func')
ret()

teacher = Teacher('may',22)    #--func--
print(teacher.__dict__)   #{'name': 'may', 'age': 22}

# print(getattr(Teacher,'name'))
print(getattr(Teacher,'__dict__'))
print(getattr(Teacher,'show_student'))

# {'学生信息': 'show_student', '讲师信息': 'show_teacher'}
# # --func--
# # {'name': 'may', 'age': 22}
# # {'__module__': '__main__', 'dic': {'学生信息': 'show_student', '讲师信息': 'show_teacher'}, '__init__': <function Teacher.__init__ at 0x0000021243FE3AE8>, 'func': <classmethod object at 0x0000021243FE8E48>, 'show_student': <function Teacher.show_student at 0x0000021243FE3BF8>, 'show_teacher': <function Teacher.show_teacher at 0x0000021243FE3C80>, '__dict__': <attribute '__dict__' of 'Teacher' objects>, '__weakref__': <attribute '__weakref__' of 'Teacher' objects>, '__doc__': None}
# # <function Teacher.show_student at 0x0000021243FE3BF8>

 

hasattr()
检查对象/类是否具有某个成员
格式：hasattr (对象/类,'成员名')
返回值：布尔值

print(hasattr(Teacher,'dic'))
print(hasattr(Teacher,'show_teacher'))

#True

#True

 

# 练习1:判断类中是否有dic静态属性

ret = hasattr(Teacher,'dic')
if ret:
    print(getattr(Teacher,'dic'))
else:
    print(False)
# {'学生信息': 'show_student', '讲师信息': 'show_teacher'}

# 练习2：根据用户输入的key来调用对应的方法。

key = input("请输入想调用的方法名：")
ret1 = hasattr(teacher,teacher.dic.get(key,''))
print(ret1)
if ret1:
    func = getattr(teacher,teacher.dic[key])
    func()
else:
    print("方法不存在")
    
# 请输入想调用的方法名：学生信息
# True
# --show student--

 

setattr()设置或添加对象/类中的成员
格式： setattr(对象,'成员名',值)
返回值：None

class A:
    pass
setattr(A,'name','johnson')
print(getattr(A,'name'))
a = A()
setattr(a,'name','john')
print(getattr(a,'name'))

# johnson
# john

 

delattr() 删除对象/类中的成员
格式：delattr(对象,成员)
返回值：None

class A:
    pass
setattr(A,'name','john')
# delattr(A,'name')
# print(getattr(A,'name'))
a = A()
setattr(a,'name','may')
print(getattr(a,'name'))
delattr(a,'name')
print(getattr(a,'name'))

# may
# john

练习：

# 第一个参数是模块名称，第二个参数是变量名称
# 练习 1：反射 test 模块中的属性、函数和类

import test
print(test.day1)
print(getattr(test, 'day1')) #反射变量
ret = getattr(test,'func1') #反射函数
ret()
A = getattr(test,'A')
a = A()
a.func2() #反射类中的函数
setattr(a,'name','zs')
print(getattr(a, 'name'))

# hahah
# 周二
# 周二
# 这是func1函数
# 这是A中的func2函数

import random
import time
ret = getattr(random,'randint')
print(ret(1, 10))
t = getattr(time,'time')
print(t())

# zs
# 6
# 1586960627.4621446

# 借助 sys 模块获取当前模块的名称。
# 练习 2：查看当前的所有模块
import sys
print(sys.modules)
name = "johnson"
print(getattr(sys.modules["__main__"],'name'))

# {'builtins': <module 'builtins' (built-in)>, 'sys': <module 'sys' (built-in)>, '_frozen_importlib': <module 'importlib._bootstrap' (frozen)>, '_imp': <module '_imp' (built-in)>, '_warnings': <module '_warnings' (built-in)>, '_thread': <module '_thread' (built-in)>, '_weakref': <module '_weakref' (built-in)>, '_frozen_importlib_external': <module 'importlib._bootstrap_external' (frozen)>, '_io': <module 'io' (built-in)>, 'marshal': <module 'marshal' (built-in)>, 'nt': <module 'nt' (built-in)>, 'winreg': <module 'winreg' (built-in)>, 'zipimport': <module 'zipimport' (built-in)>, 'encodings': <module 'encodings' from 'E:\\programfiles\\python\\lib\\encodings\\__init__.py'>, 'codecs': <module 'codecs' from 'E:\\programfiles\\python\\lib\\codecs.py'>, '_codecs': <module '_codecs' (built-in)>, 'encodings.aliases': <module 'encodings.aliases' from 'E:\\programfiles\\python\\lib\\encodings\\aliases.py'>, 'encodings.utf_8': <module 'encodings.utf_8' from 'E:\\programfiles\\python\\lib\\encodings\\utf_8.py'>, '_signal': <module '_signal' (built-in)>, '__main__': <module '__main__' from 'E:/All_Project_Entry/Python/Python全面学习/3.类/22.类的常用函数.py'>, 'encodings.latin_1': <module 'encodings.latin_1' from 'E:\\programfiles\\python\\lib\\encodings\\latin_1.py'>, 'io': <module 'io' from 'E:\\programfiles\\python\\lib\\io.py'>, 'abc': <module 'abc' from 'E:\\programfiles\\python\\lib\\abc.py'>, '_weakrefset': <module '_weakrefset' from 'E:\\programfiles\\python\\lib\\_weakrefset.py'>, 'site': <module 'site' from 'E:\\programfiles\\python\\lib\\site.py'>, 'os': <module 'os' from 'E:\\programfiles\\python\\lib\\os.py'>, 'errno': <module 'errno' (built-in)>, 'stat': <module 'stat' from 'E:\\programfiles\\python\\lib\\stat.py'>, '_stat': <module '_stat' (built-in)>, 'ntpath': <module 'ntpath' from 'E:\\programfiles\\python\\lib\\ntpath.py'>, 'genericpath': <module 'genericpath' from 'E:\\programfiles\\python\\lib\\genericpath.py'>, 'os.path': <module 'ntpath' from 'E:\\programfiles\\python\\lib\\ntpath.py'>, '_collections_abc': <module '_collections_abc' from 'E:\\programfiles\\python\\lib\\_collections_abc.py'>, '_sitebuiltins': <module '_sitebuiltins' from 'E:\\programfiles\\python\\lib\\_sitebuiltins.py'>, 'sysconfig': <module 'sysconfig' from 'E:\\programfiles\\python\\lib\\sysconfig.py'>, '_bootlocale': <module '_bootlocale' from 'E:\\programfiles\\python\\lib\\_bootlocale.py'>, '_locale': <module '_locale' (built-in)>, 'encodings.gbk': <module 'encodings.gbk' from 'E:\\programfiles\\python\\lib\\encodings\\gbk.py'>, '_codecs_cn': <module '_codecs_cn' (built-in)>, '_multibytecodec': <module '_multibytecodec' (built-in)>, 'types': <module 'types' from 'E:\\programfiles\\python\\lib\\types.py'>, 'functools': <module 'functools' from 'E:\\programfiles\\python\\lib\\functools.py'>, '_functools': <module '_functools' (built-in)>, 'collections': <module 'collections' from 'E:\\programfiles\\python\\lib\\collections\\__init__.py'>, 'operator': <module 'operator' from 'E:\\programfiles\\python\\lib\\operator.py'>, '_operator': <module '_operator' (built-in)>, 'keyword': <module 'keyword' from 'E:\\programfiles\\python\\lib\\keyword.py'>, 'heapq': <module 'heapq' from 'E:\\programfiles\\python\\lib\\heapq.py'>, '_heapq': <module '_heapq' (built-in)>, 'itertools': <module 'itertools' (built-in)>, 'reprlib': <module 'reprlib' from 'E:\\programfiles\\python\\lib\\reprlib.py'>, '_collections': <module '_collections' (built-in)>, 'weakref': <module 'weakref' from 'E:\\programfiles\\python\\lib\\weakref.py'>, 'collections.abc': <module 'collections.abc' from 'E:\\programfiles\\python\\lib\\collections\\abc.py'>, 'importlib': <module 'importlib' from 'E:\\programfiles\\python\\lib\\importlib\\__init__.py'>, 'importlib._bootstrap': <module 'importlib._bootstrap' (frozen)>, 'importlib._bootstrap_external': <module 'importlib._bootstrap_external' (frozen)>, 'warnings': <module 'warnings' from 'E:\\programfiles\\python\\lib\\warnings.py'>, 'importlib.util': <module 'importlib.util' from 'E:\\programfiles\\python\\lib\\importlib\\util.py'>, 'importlib.abc': <module 'importlib.abc' from 'E:\\programfiles\\python\\lib\\importlib\\abc.py'>, 'importlib.machinery': <module 'importlib.machinery' from 'E:\\programfiles\\python\\lib\\importlib\\machinery.py'>, 'contextlib': <module 'contextlib' from 'E:\\programfiles\\python\\lib\\contextlib.py'>, 'backports': <module 'backports' from 'E:\\programfiles\\python\\lib\\site-packages\\backports\\__init__.py'>, 'sitecustomize': <module 'sitecustomize' from 'E:\\Program Files\\JetBrains\\PyCharm 2019.2.1\\helpers\\pycharm_matplotlib_backend\\sitecustomize.py'>, 'test': <module 'test' from 'E:\\All_Project_Entry\\Python\\Python全面学习\\3.类\\test.py'>, 'random': <module 'random' from 'E:\\programfiles\\python\\lib\\random.py'>, 'math': <module 'math' (built-in)>, 'hashlib': <module 'hashlib' from 'E:\\programfiles\\python\\lib\\hashlib.py'>, '_hashlib': <module '_hashlib' from 'E:\\programfiles\\python\\DLLs\\_hashlib.pyd'>, '_blake2': <module '_blake2' (built-in)>, '_sha3': <module '_sha3' (built-in)>, 'bisect': <module 'bisect' from 'E:\\programfiles\\python\\lib\\bisect.py'>, '_bisect': <module '_bisect' (built-in)>, '_random': <module '_random' (built-in)>, 'time': <module 'time' (built-in)>}
# johnson