[TOC] # 反射操作 ## `__import__`：動態導入模塊 ~~~ index = __import__('index') index.sayHello() ~~~ ## isinstance：判斷對象是否是類或者類型元組中任意類元素的實例 ~~~ >>> isinstance(1,int) True >>> isinstance(1,str) False >>> isinstance(1,(int,str)) True ~~~ ## issubclass：判斷類是否是另外一個類或者類型元組中任意類元素的子類 ~~~ >>> issubclass(bool,int) True >>> issubclass(bool,str) False >>> issubclass(bool,(str,int)) True ~~~ ## hasattr：檢查對象是否含有屬性 ~~~ #定義類A >>> class Student: def __init__(self,name): self.name = name >>> s = Student('Aim') >>> hasattr(s,'name') #a含有name屬性 True >>> hasattr(s,'age') #a不含有age屬性 False ~~~ ## getattr：獲取對象的屬性值 ~~~ #定義類Student >>> class Student: def __init__(self,name): self.name = name >>> getattr(s,'name') #存在屬性name 'Aim' >>> getattr(s,'age',6) #不存在屬性age，但提供了默認值，返回默認值 >>> getattr(s,'age') #不存在屬性age，未提供默認值，調用報錯 Traceback (most recent call last): File "<pyshell#17>", line 1, in <module> getattr(s,'age') AttributeError: 'Stduent' object has no attribute 'age' ~~~ ## setattr：設置對象的屬性值 ~~~ >>> class Student: def __init__(self,name): self.name = name >>> a = Student('Kim') >>> a.name 'Kim' >>> setattr(a,'name','Bob') >>> a.name 'Bob' ~~~ ## delattr：刪除對象的屬性 ~~~ #定義類A >>> class A: def __init__(self,name): self.name = name def sayHello(self): print('hello',self.name) #測試屬性和方法 >>> a.name '小麥' >>> a.sayHello() hello 小麥 #刪除屬性 >>> 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：檢測對象是否可被調用 ~~~ >>> class B: #定義類B def __call__(self): print('instances are callable now.') >>> callable(B) #類B是可調用對象 True >>> b = B() #調用類B >>> callable(b) #實例b是可調用對象 True >>> b() #調用實例b成功 instances are callable now. ~~~ # 變量操作 ## globals：返回當前作用域內的全局變量和其值組成的字典 ~~~ >>> globals() {'__spec__': None, '__package__': None, '__builtins__': <module 'builtins' (built-in)>, '__name__': '__main__', '__doc__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>} >>> a = 1 >>> globals() #多了一個a {'__spec__': None, '__package__': None, '__builtins__': <module 'builtins' (built-in)>, 'a': 1, '__name__': '__main__', '__doc__': None, '__loader__': <class '_frozen_importlib.BuiltinImporter'>} ~~~ ## locals：返回當前作用域內的局部變量和其值組成的字典 ~~~ >>> def f(): print('before define a ') print(locals()) #作用域內無變量 a = 1 print('after define a') print(locals()) #作用域內有一個a變量，值為1 >>> f <function f at 0x03D40588> >>> f() before define a {} after define a {'a': 1} ~~~