[TOC] # 反射操作 ## `__import__`：动态导入模块 ~~~ index = __import__('index') index.sayHello() ~~~ ## isinstance：判断对象是否是类或者类型元组中任意类元素的实例 ~~~ >>> isinstance(1,int) True >>> isinstance(1,str) False >>> isinstance(1,(int,str)) True ~~~ ## issubclass：判断类是否是另外一个类或者类型元组中任意类元素的子类 ~~~ >>> issubclass(bool,int) True >>> issubclass(bool,str) False >>> issubclass(bool,(str,int)) True ~~~ ## hasattr：检查对象是否含有属性 ~~~ #定义类A >>> class Student: def __init__(self,name): self.name = name >>> s = Student('Aim') >>> hasattr(s,'name') #a含有name属性 True >>> hasattr(s,'age') #a不含有age属性 False ~~~ ## getattr：获取对象的属性值 ~~~ #定义类Student >>> class Student: def __init__(self,name): self.name = name >>> getattr(s,'name') #存在属性name 'Aim' >>> getattr(s,'age',6) #不存在属性age，但提供了默认值，返回默认值 >>> getattr(s,'age') #不存在属性age，未提供默认值，调用报错 Traceback (most recent call last): File "<pyshell#17>", line 1, in <module> getattr(s,'age') AttributeError: 'Stduent' object has no attribute 'age' ~~~ ## setattr：设置对象的属性值 ~~~ >>> class Student: def __init__(self,name): self.name = name >>> a = Student('Kim') >>> a.name 'Kim' >>> setattr(a,'name','Bob') >>> a.name 'Bob' ~~~ ## delattr：删除对象的属性 ~~~ #定义类A >>> class A: def __init__(self,name): self.name = name def sayHello(self): print('hello',self.name) #测试属性和方法 >>> a.name '小麦' >>> a.sayHello() hello 小麦 #删除属性 >>> delattr(a,'name') >>> a.name Traceback (most recent call last): File "<pyshell#47>", line 1, in <module> a.name AttributeError: 'A' object has no attribute 'name' ~~~ ## callable：检测对象是否可被调用 ~~~ >>> class B: #定义类B def __call__(self): print('instances are callable now.') >>> callable(B) #类B是可调用对象 True >>> b = B() #调用类B >>> callable(b) #实例b是可调用对象 True >>> b() #调用实例b成功 instances are callable now. ~~~ # 变量操作 ## globals：返回当前作用域内的全局变量和其值组成的字典 ~~~ >>> globals() {'__spec__': None, '__package__': None, '__builtins__': <module 'builtins' (built-in)>, '__name__': '__main__', '__doc__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>} >>> a = 1 >>> globals() #多了一个a {'__spec__': None, '__package__': None, '__builtins__': <module 'builtins' (built-in)>, 'a': 1, '__name__': '__main__', '__doc__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>} ~~~ ## locals：返回当前作用域内的局部变量和其值组成的字典 ~~~ >>> def f(): print('before define a ') print(locals()) #作用域内无变量 a = 1 print('after define a') print(locals()) #作用域内有一个a变量，值为1 >>> f <function f at 0x03D40588> >>> f() before define a {} after define a {'a': 1} ~~~