類結構中的變量初始化

Question

我想在init中初始化一個函數/方法。 因此，類A中的self.y返回正確的值10.或者可能在A中使用方法get_y？

請參考下面的代碼和註釋。如圖所示感謝

class A(object): 
    def __init__(self): 
     self.x = 5 
     self.y = None 
     # self.y = B.eval(self)?? # wants y to be a value obtained from B.eval() 
    def get_x(self): 
     return self.x 

    def get_y(self): 
     # wants y to be a value obtained from B.eval() 
     #return B.eval(self) ?? 

class B(object): 
    def eval(ClassA): 
     """ 
     :param ClassA: is an instance of A 
     :return: value 
     """ 
     return ClassA.get_x() + 5 


a = A() 
b = B() 
print(a.get_y()) # wants value 10 printed out here 
print(B.eval(a)) 

Answer 1

只是要B.eval()一個classmethod使用它作爲class B的方法裝飾：

class A(object): 
    def __init__(self): 
     self.x = 5 
     self.y = None 
     self.y = B.eval(self) 
    def get_x(self): 
     return self.x 

    def get_y(self): 
     return B.eval(self) 

class B(object): 
    @staticmethod # ADD THIS LINE 
    def eval(ClassA): 
     """ 
     :param ClassA: is an instance of A 
     :return: value 
     """ 
     return ClassA.get_x() + 5 

a = A() 
b = B() 
print(a.get_y()) # -> 10 
print(B.eval(a)) # -> 10