模块无法识别我的功能

Question

我有一个Fraction类的代码

class Fraction:

    def __init__(self,top,bottom):  
        self.num = top  
        self.den = bottom  

    def __str__(self):  
        return str(self.num)+"/"+str(self.den)  

    def show(self):  
        print(self.num,"/",self.den)  

    def gcd(m,n):  
        while m%n != 0:  
            oldm = m  
            oldn = n  
            m = oldn  
            n = oldm%oldn  
        return n  


    def __add__(self,otherfraction):  
        newnum = self.num*otherfraction.den + \  
                     self.den*otherfraction.num  
        newden = self.den * otherfraction.den  
        common = gcd(newnum,newden)  
        return Fraction(newnum//common,newden//common)  

    def __eq__(self, other):  
        firstnum = self.num * other.den  
        secondnum = other.num * self.den    
        return firstnum == secondnum

当我运行它并尝试添加两个分数时，会弹出说

File "/Users/----/Downloads/Listings/listing_1_9.py", line 25,  
 in __add__
    common = gcd(newnum,newden)  
NameError: global name 'gcd' is not defined

Answer 1

在您的代码中，gcd是一种分数方法，因此在从另一种方法中引用它时应使用self.gcd。

Answer 2

改为使用self.gcd。

解释

NameError: global name 'gcd' is not defined

那是因为gcd不是全球性的。它是Fraction的方法。