在python中,当在派生类中调用某个方法时,如何调用基类函数?
我正在用类似python的语言定义一个基类在python中,当在派生类中调用某个方法时,如何调用基类函数?,python,inheritance,Python,Inheritance,我正在用类似python的语言定义一个基类 class Base(object): def __init__(self): self._changed = False 以及一些派生类: class Car(Base): def set_type(self, type_): # do something def set_mileage(self, mileage): # do something class Flowe
class Base(object):
def __init__(self):
self._changed = False
以及一些派生类:
class Car(Base):
def set_type(self, type_):
# do something
def set_mileage(self, mileage):
# do something
class Flower(base):
def set_name(self, name):
# do something
在本例中,我现在希望在调用某个派生类的set
方法时,将属性“\u changed”设置为True
。我可以简单地添加一行
self._changed = True
对于每个set
方法,或者使用decorator,但我正在寻找一种更方便、更自动的方法,每当调用一个名称以“set\”开头的方法时都可以这样做。我正在考虑使用\uuuu getattribute\uuuu
类似于以下未尝试(且不起作用)的示例:
def __getattribute__(self, name):
if name.startswith('set_'):
self._changed = True
return self.__getattribute__(name)
那么如何以正确的方式实现它呢?我会为此使用一个装饰器。类似这样的东西(未经测试): 然后在任何get方法中,您只需执行此操作即可
@isGet
def set_mileage(self, mileage):
# dosomething
更新:这是一个完全有效的示例,它使用了一个元类和一个描述符以及setter和getter:
class Field(object):
def __get__(self, ins, type):
return getattr(ins, self.field_name, None)
def __set__(self, ins, val):
setattr(ins, self.field_name, val)
ins._changed = True
class Meta(type):
def __new__(cls, clsname, bases, dct):
for k, v in dct.items():
if isinstance(v, Field):
v.field_name = '_' + k
return type.__new__(cls, clsname, bases, dct)
class Base(object):
__metaclass__ = Meta
def __init__(self):
self._changed = False
class Car(Base):
type = Field()
mileage = Field()
class Flower(Base):
name = Field()
演示:
>>> c = Car()
>>> c._changed
False
>>> c.type = "4X4"
>>> c._changed
True
>>> c1 = Car()
>>> c1._changed
False
>>> c1.mileage = 100
>>> c1._changed
True
>>> c.type
'4X4'
>>> c1.mileage
100
>>> f = Flower()
>>> f._changed
False
>>> f.name = "Rose"
>>> f._changed
True
>>> f.name
'Rose'
元类可以在这里工作:
from types import FunctionType
from functools import wraps
class Setter(type):
def __new__(cls, clsname, bases, dct):
for item in dct:
if item.startswith("set_") and isinstance(dct[item], FunctionType):
dct[item] = cls.changer(dct[item])
return super(Setter, cls).__new__(cls, clsname, bases, dct)
@staticmethod
def changer(func):
@wraps(func)
def wrapper(self, *args, **kwargs):
self._changed = True
return func(self, *args, **kwargs)
return wrapper
class Base(object):
__metaclass__ = Setter
def __init__(self):
self._changed = False
然后像平常一样从Base继承
示例用法:
>>> from meta import Car
>>> c = Car()
>>> c._changed
False
>>> c.set_type("blah")
ok
>>> c._changed
True
元类只是自动修饰类“
\uuu dict\uuu
中以set\u
开头的任何方法。我也想到了一个修饰器,但你仍然需要定义它。你需要定义方法的名称(从set
开始,你必须定义修饰器).为了不忘记decorator,最好是任何set
方法自动调用基类中的某个方法。。。。
>>> from meta import Car
>>> c = Car()
>>> c._changed
False
>>> c.set_type("blah")
ok
>>> c._changed
True