写了一个类继承的函数,结果子类在调用父类实例方法以后,新建对象,print输出的值为None,网上查了也没查到原因
class classA(object):
def init(self, attribute_parameter1="Volkswagen", attribute_parameter2="Mercedes Benz"):
self.attribute_A1, self.attribute_A2 = attribute_parameter1, attribute_parameter2
def __str__(self):
return "\"测试用父类A\""
def __del__(self):
return f"已删除{classA.__str__(self)}"
def classAFunction(self, parameter1="BMW", parameter2="Audi"):
information_A = f"{classA.__str__(self)}的实例属性是{self.attribute_A1}和{self.attribute_A2},实例方法的参数是{parameter1}和{parameter2}"
return information_A, parameter1 + "," + parameter2
class classB(classA):
def init(self, attribute_parameter1="Volkswagen", attribute_parameter2="Mercedes Benz"):
super(classA, self).init()
self.attribute_A1, self.attribute_A2 = attribute_parameter1, attribute_parameter2
def newClassAFunction(self, parameter1, parameter2):
classA.__init__(self)
classA.classAFunction(self, parameter1, parameter2)
result = classB()
result.newClassAFunction(parameter1="BMW", parameter2="Audi")
print(result.newClassAFunction(parameter1="BMW", parameter2="Audi"))
没报错,但是运行结果是"None"
试过把"return information_A, parameter1 + "," + parameter2"里面的"return"改为print,结果能返回正确值
但是我不明白,def 函数不是必须要return一个结果给函数么,为何我用了return反而返回None,用print能输出正确值,想错误的原因,非常感谢!