反射是指通过字符串映射或修改程序运行时的状态、属性、方法, 有以下4个方法
1.getattr(object, name, default = None)
根据字符串获取 obj 对象里对应 str 方法的内存地址
示例：
class Dog(object):
def __init__(self, name):
self.name = name def eat(self, food):
print('%s is eating %s' % (self.name, food)) dog1 = Dog('Dog1')
choice = input('>>').strip()
if hasattr(dog1, choice):
getattr(dog1, choice)('bone') # 根据字符串获取对象里对应方法的内存地址，传入‘bone’执行
print(getattr(dog1, choice)) # 打印属性
输出结果：
>>eat
Dog1 is eating bone
<bound method Dog.eat of <__main__.Dog object at 0x00000249C4C3B780>>
2.hasattr(object, name)
判断一个 obj 对象里是否有对应 str 字符串
示例：
class Dog(object):
def __init__(self, name):
self.name = name def eat(self, food):
print('%s is eating %s' % (self.name, food)) dog1 = Dog('Dog1')
choice = input('>>').strip()
print(hasattr(dog1, choice)) # 判断一个 obj 对象里是否有对应 str 字符串
输出结果：
>>eat
True
3.setattr(object, y, v)
给类新加了一个属性等于： obj.y = v
传入属性示例：
class Dog(object):
def __init__(self, name):
self.name = name def eat(self, food):
print('%s is eating %s' % (self.name, food)) dog1 = Dog('Dog1')
choice = input('>>').strip()
print(hasattr(dog1, choice)) # 判断一个 obj 对象里是否有对应 str 字符串
if hasattr(dog1, choice):
print(getattr(dog1, choice)) # 打印修改前的属性
setattr(dog1, choice, 'Dog2') # 如果属性存在，可以通过 setattr 进行修改
print(getattr(dog1, choice)) # 打印修改后的属性
else:
setattr(dog1, choice, None) # 给类新加了一个属性 == dog1.choice = None
print(getattr(dog1, choice)) # 打印新加入的属性
修改已有属性输出结果：
>>name
True
Dog1
Dog2
增加新的属性输出结果：
>>age
False
None
传入方法示例：
class Dog(object):
def __init__(self, name):
self.name = name def eat(self, food):
print('%s is eating %s' % (self.name, food)) def bulk(self): # 传入方法需要提前写好
print('%s: woof,woof!' % self.name) dog1 = Dog('Dog1')
choice = input('>>').strip()
print(hasattr(dog1, choice)) # 判断一个 obj 对象里是否有对应 str 字符串
if hasattr(dog1, choice):
pass
else:
setattr(dog1, choice, bulk) # 给类新加了一个方法
dog1.bulk(dog1) # 调用新加入的方法 bulk
输出结果：
>>bulk
False
Dog1: woof,woof!
4.delattr(object, name)
删除 obj 对象中对应属性
示例：
class Dog(object):
def __init__(self, name):
self.name = name def eat(self, food):
print('%s is eating %s' % (self.name, food)) dog1 = Dog('Dog1')
choice = input('>>').strip()
print(hasattr(dog1, choice)) # 输出 True
if hasattr(dog1, choice):
delattr(dog1, choice)
print(getattr(dog1, choice)) # 打印会报错