Python类中方法getitem和getattr详解

class Foo(object):
  def __init__(self):
    self.name = 'jack'

  def __getitem__(self,item):
    if item in self.__dict__:    # item = key，判断该key是否存在对象的 __dict__ 里，
      return self.__dict__[item] # 返回该对象 __dict__ 里key对应的value

  def __setitem__(self, key, value):
    self.__dict__[key] = value   # 在对象 __dict__ 为指定的key设置value

  def __delitem__(self, key):
    del self.__dict__[key]     # 在对象 __dict__ 里删除指定的key

f1 = Foo()
print(f1['name'])  # jack
f1['age'] =10    
print(f1['age'])  # 10
del f1['name']
print(f1.__dict__) # {'age': 10}

class Foo(object):
  def __init__(self):
    self.name = 'jack'

  def __getattr__(self, item):
    if item in self.__dict__:
      return self.__dict__[item]

  def __setattr__(self, key, value):
    self.__dict__[key] = value

  def __delattr__(self, item):
    del self.__dict__[item]

c1 = Foo()
print(c1.name) # jack
c1.age = 18
print(c1.age)  # 18
del c1.age   # 删除 对象c1的age
print(c1.age)  # None