類型錯誤：不受約束的方法MULT（）必須與calculadora實例作爲第一個參數來調用（得不是int實例）

Question

我得到一個 類型錯誤：不受約束的方法MULT（）必須與calculadora實例作爲第一個參數來調用（有INT實例，而不是）上運行我的Python文件時

：

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

如果您要訪問的方法爲靜態方法（accesing沒有CLAS實例方法），你需要@staticmethod來裝點他們：

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) 

---

如果你的意思是實例方法，你需要先創建實例。並需要修改方法的簽名，包括self作爲第一個參數：

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)