python中的特殊属性

# animal.py class Animal: x = 123 def __init__(self, name): self.name = name self.age = 20 self.weight = 20 y = 200 print('animal Module\'s names = {}'.format(dir())) # 模块的属性 # animal Module's names = ['Animal', '__annotations__', '__builtins__', '__cached__', '__doc__', '__file__', # '__loader__', '__name__', '__package__', '__spec__', 'y'] # cat.py import animal from animal import Animal class Cat(Animal): x = 'cat' y = 'abcd' class Dog(Animal): def __dir__(self): # 返回可迭代对象的返回值 return ['dog'] # 必须返回可迭代对象，其内容必须是字符串 print('Current Module\'s names = {}'.format(dir())) print('Current Module\'s names = {}'.format(dir(animal))) # animal Module's names = ['Animal', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', # '__name__', '__package__', '__spec__'] # Current Module's names = ['Animal', 'Cat', 'Dog', '__annotations__', '__builtins__', '__cached__', '__doc__', # '__file__', '__loader__', '__name__', '__package__', '__spec__', 'animal'] print("object's __dict__ = {}".format(sorted(object.__dict__.keys()))) # object's __dict__ = ['__class__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', # '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__ne__', '__new__', # '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__'] print("Animal's dir() = {}".format(dir(Animal))) # 类Animal的dir() # Animal's dir() = ['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', # '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', # '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', # '__subclasshook__', '__weakref__', 'x'] print("Cat's dir() = {}".format(dir(Cat))) # 类Cat的dir() # Cat's dir() = ['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', # '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', # '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', # '__str__', '__subclasshook__', '__weakref__', 'x', 'y'] print('~~~~~~~~~~~~~~~~') tom = Cat('tom') print(sorted(dir(tom))) # 实例tom的属性、Cat类及所有祖先类的类属性 print(sorted(tom.__dir__())) # 同上 # ['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', # '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', # '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', # 'age', 'name', 'weight', 'x', 'y'] print("Dog's dir = {}".format(dir(Dog))) # Animal类中的x也在其中 dog = Dog('snoppy') print(dir(dog)) # ['dog'] print(dog.__dict__) # {'name': 'snoppy', 'age': 20, 'weight': 20}

内建函数

1. locals()返回当前作用域中的变量字典

2. globals当前模块全局变量的字典

class Person: def show(self): a = 100 t = int(a) print(1, dir()) # 结果为列表 1 ['a', 'self', 't'] print(2, locals()) # 结果为字典 2 {'t': 100, 'a': 100, 'self': <__main__.Person object at 0x0000000001E496A0>} print(3, locals().keys()) def test(a=50, b=100): c = 180 print(4, dir()) # 4 ['a', 'b', 'c'] print(5, locals()) # 5 {'c': 180, 'b': 100, 'a': 50} Person().show() test() print(6, dir()) # 6,7,8三者的结果一样 print(7, sorted(locals().keys())) # globals和locals返回时字典 print(8, sorted(globals().keys())) # 8 ['Animal', 'Person', '__annotations__', '__builtins__', '__cached__', '__doc__', '__file__', '__loader__', # '__name__', '__package__', '__spec__', 'test', 'y']