如何使 __str__ 或 __repr__ 返回当前类的名称？

Question

我有这个代码：

class Employee:
    def __init__(self, name, pay, gender):
        self.name = name
        self.pay = pay
        self.gender = gender

    def add_raise(self):
        self.pay = int(self.pay*1.10)

    def __str__(self):
        if self.gender == "Female" or self.gender == "female":
            return f"{__class__.__name__} name: {self.name}, and she earns {self.pay} Pound"
        else:
            return f"{__class__.__name__} name: {self.name}, and he earns {self.pay} Pound"

    def __repr__(self):
        if self.gender == "Female" or self.gender == "female":
            return f"{__class__.__name__} name: {self.name}, and she earns {self.pay} Pound"
        else:
            return f"{__class__.__name__} name: {self.name}, and he earns {self.pay} Pound"

class Supervisor(Employee):
    def __init__(self, name, pay, gender, department):
        super().__init__(name, pay, gender)
        self.department = department

现在，当我尝试跑步时

emp1 = Employee("Ron", 1000, "male")
emp10 = Supervisor("Hermoine", 3000, "female", "General")
print(emp1, emp10)

我一开始只得到“员工姓名”。我如何更改它以反映“Hermoine”是 aSupervisor而不仅仅是Employee，而不重写__str__和__repr__方法？

Answer 1

解决方案：

尝试将您的第一堂课更改为：

class Employee:
    def __init__(self, name, pay, gender):
        self.name = name
        self.pay = pay
        self.gender = gender

    def add_raise(self):
        self.pay = int(self.pay*1.10)

    def __str__(self):
        if self.gender == "Female" or self.gender == "female":
            return f"{self.__class__.__name__} name: {self.name}, and she earns {self.pay} Pound"
        else:
            return f"{self.__class__.__name__} name: {self.name}, and he earns {self.pay} Pound"

    def __repr__(self):
        if self.gender == "Female" or self.gender == "female":
            return f"{self.__class__.__name__} name: {self.name}, and she earns {self.pay} Pound"
        else:
            return f"{self.__class__.__name__} name: {self.name}, and he earns {self.pay} Pound"

尝试self.__class__.__name__代替__class__.__name__所有字符串。

现在：

emp1 = Employee("Ron", 1000, "male")
emp10 = Supervisor("Hermoine", 3000, "female", "General")
print(emp1, emp10)

输出：

class Employee:
    def __init__(self, name, pay, gender):
        self.name = name
        self.pay = pay
        self.gender = gender

    def add_raise(self):
        self.pay = int(self.pay*1.10)

    def __str__(self):
        if self.gender == "Female" or self.gender == "female":
            return f"{self.__class__.__name__} name: {self.name}, and she earns {self.pay} Pound"
        else:
            return f"{self.__class__.__name__} name: {self.name}, and he earns {self.pay} Pound"

    def __repr__(self):
        if self.gender == "Female" or self.gender == "female":
            return f"{self.__class__.__name__} name: {self.name}, and she earns {self.pay} Pound"
        else:
            return f"{self.__class__.__name__} name: {self.name}, and he earns {self.pay} Pound"

解释：

之所以self返回实际的类名是因为它会从当前实例中提取类名self。没有的self话只会得到原始父类的类名，而不是它当前所在的实际类，这就是原因self如此重要。

另外，正如 @MadPhysicist 提到的，它“因为__class__在类执行时在词法范围内”。