类型错误：必须使用 calculadora 实例作为第一个参数调用未绑定的方法 mult()（改为获取 int 实例）

Question

我得到一个 TypeError: unbound method mult() must be called with calculadora instance 作为第一个参数（取而代之的是 int 实例）

运行我的 python 文件时：

    from __future__ import print_function

class calculadora:


    def suma(x,y):
        added = x + y
        print(added)

    def resta(x,y):
        sub = x - y
        print(sub)

    def mult(x,y):
        multi = x * y
        print(multi)


calculadora.mult(3,5)

Answer 1

如果你想以静态方法访问方法（访问方法没有 clas 实例），你需要用@staticmethod装饰它们：

class calculadora:
    @staticmethod
    def suma(x, y):
        added = x + y
        print(added)

    @staticmethod
    def resta(x, y):
        sub = x - y
        print(sub)

    @staticmethod
    def mult(x, y):
        multi = x * y
        print(multi)

---

如果您指的是实例方法，则需要先创建实例。并且需要修改方法的签名以包含self作为第一个参数：

class calculadora:
    def suma(self, x, y): # not `self`, refering class instance
        added = x + y
        print(added)

    def resta(self, x, y):
        sub = x - y
        print(sub)

    def mult(self, x, y):
        multi = x * y
        print(multi)


c = calculadora()  # Create instance
c.mult(3,5)  # Access the method through instance, (not class)