python：在类中定义装饰器函数时出错，该如何解决？

Question

#学生类
class Stu:
    def __init__(self,name,grade):
        self.name=name    #名字
        self.grade=grade    #分数
    
    def printout(self):
        print("name:{0} grade:{1}".format(str(self.name),str(self.grade)))    #格式化输出

    def plusDouble(self,plus_fun):    #装饰器函数
        def inner():
            return str(plus_fun())+"分"
        return inner

    @plusDouble 
    def plus(self,num):
        self.grade=self.grade+num
        return self.grade    #返回加分后的结果

#测试
student=Stu("zhangsan",20)
student.printout()
student.plus(20)
student.printout()

报错的结果：

Traceback (most recent call last):
  File "E:\eclipse\eclipse\plugins\org.python.pydev_4.5.5.201603221110\pysrc\pydevd.py", line 1529, in <module>
    globals = debugger.run(setup['file'], None, None, is_module)
  File "E:\eclipse\eclipse\plugins\org.python.pydev_4.5.5.201603221110\pysrc\pydevd.py", line 936, in run
    pydev_imports.execfile(file, globals, locals)  # execute the script
  File "E:\eclipse\eclipse\plugins\org.python.pydev_4.5.5.201603221110\pysrc\_pydev_imps\_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "E:\workplace\PlayPy\Play.py", line 14, in <module>
    class Stu:
  File "E:\workplace\PlayPy\Play.py", line 27, in Stu
    @plusDouble 
TypeError: plusDouble() missing 1 required positional argument: 'plus_fun'

TypeError: plusDouble() missing 1 required positional argument: 'plus_fun'
这该怎么办？

Answer 1

# coding: utf-8

def plusDouble(plus_fun):    #装饰器函数
    def inner(self, num):
        return str(plus_fun(self, num))+"分"
    return inner

class Stu:
    def __init__(self,name,grade):
        self.name=name    #名字
        self.grade=grade    #分数

    def printout(self):
        print("name:{0} grade:{1}".format(str(self.name),str(self.grade)))    #格式化输出

    @plusDouble
    def plus(self,num):
        self.grade=self.grade+num
        return self.grade    #返回加分后的结果

#测试
student=Stu("zhangsan",20)
student.printout()
student.plus(20)
student.printout()

Answer 2

报错很清楚啊… plusDouble少一个参数。作为一个类方法的plusDouble是有两个参数的… 它作为装饰器的时候你只传了一个参数进去，plus = plusDouble(plus) 当然是少一个参数了。

Answer 3

#学生类
class Stu:
    def __init__(self,name,grade):
        self.name=name    #名字
        self.grade=grade    #分数
    
    def printout(self):
        print("name:{0} grade:{1}".format(str(self.name),str(self.grade)))    #格式化输出

    def _plusDouble(plus_fun):    #装饰器函数
        def inner(self,num):
            return str(plus_fun(self, num))+"分"
        return inner

    @_plusDouble 
    def plus(self,num):
        self.grade=self.grade+num
        return self.grade    #返回加分后的结果

#测试
student=Stu("zhangsan",20)
student.printout()
student.plus(20)
student.printout()