面向对象——反射

• 反射：通过字符串的形式操作对象相关的属性，python中一切皆对象（都可以使用反射）
• hasattr(object,name)：判断object中有没有一个name字符串对应的方法或属性
• getattr(object, name, default=None)

• def getattr(object, name, default=None): # known special case of getattr
      """
      getattr(object, name[, default]) -> value
  
      Get a named attribute from an object; getattr(x, 'y') is equivalent to x.y.
      When a default argument is given, it is returned when the attribute doesn't
      exist; without it, an exception is raised in that case.
      """
      pass

• setattr(x, y, v)

• def setattr(x, y, v): # real signature unknown; restored from __doc__
      """
      Sets the named attribute on the given object to the specified value.
  
      setattr(x, 'y', v) is equivalent to ``x.y = v''
      """
      pas

• delattr(x, y)

• def delattr(x, y): # real signature unknown; restored from __doc__
      """
      Deletes the named attribute from the given object.
  
      delattr(x, 'y') is equivalent to ``del x.y''
      """
      pass

• class People:
      country='China'
  
      def __init__(self,name,age):
          self.name=name
          self.age=age
  
      def talk(self):
          print('%s is talking' %self.name)
  obj=People('egon',18)
  #通常情况下：
  # print(obj.name) #egon
  # print(obj.talk)#<bound method People.talk of <__main__.People object at 0x000000000287ACC0>>
  #
  # choice = input("==>:")##choice='name'
  # print(object.choice)#object.'name'，报错
  #字符串映射
  
  #检测是否含有某属性
  # print(hasattr(obj,'name')) #True
  # print(hasattr(obj,'talk')) #True
  # print(hasattr(obj,'run'))#False
  
  #获取属性
  # print(getattr(obj,'name'))#egon
  # print(getattr(obj,'run'))#报错
  # print(getattr(obj,'run',None))#None
  # fun = getattr(obj,'talk')
  # fun()#egon is talking
  
  #设置属性
  setattr(obj,'sex','male')  #obj.sex = male
  print(obj.sex)#male
  setattr(obj,'show_name',lambda self : self.name+'_s')#设置方法
  print(obj.show_name(obj))#egon_s
  print(obj.__dict__)
  #{'name': 'egon', 'age': 18, 'sex': 'male', 'show_name': <function <lambda> at 0x0000000001CF2E18>}
  
  #删除属性
  delattr(obj,'age')
  delattr(obj,'show_name')
  print(obj.__dict__)#{'name': 'egon', 'sex': 'male'}
  delattr(obj,'age')#不存在，则报错

  class Foo:
      staticField = 'old boy'
      def __init__(self):
          self.name = 'wupeiqi'
      @classmethod
      def func(self):
          return 'func'
      @staticmethod
      def bar():
          return 'bar'
  print(getattr(Foo,'staticField'))#old boy
  print(getattr(Foo,'func'))#<bound method Foo.func of <class '__main__.Foo'>>
  print(getattr(Foo,'bar'))#<function Foo.bar at 0x0000000001E84510>