为什么python在此类的第二个方法上抛出错误？

Question

Why is is python throwing error at the second method in of this class?

class Lutany:
    formulaa = 0
    formulab = 0
    def __init__(self,num):
        self.num = num
        self.formulaa = self.formulaA()
        self.formulab = self.formulaB


    def formulaA(self):
        q = 0
        num = self.num
        while num > 0 :
            q += num + (num - 1)
            num = num - 1
        return q
        self.formulab = formulaB()

    def formulaB(self):
        num = self.num
        q = 0
        while num > 0 :
            q = q + (num * num)
            num = num - 1
        return (0.5 * q)


if(__name__ == '__main__'):

    l = Lutany(675)

    p = l.formulaa
    q = l.formulab 

    print " FormunlA returned " , str(p) , "  for 675 "
    print " FormulaB returned " , str(q) , "  for 675 " 

When running I have the following error:

~$ python lutany.py
Traceback (most recent call last):
File "lutany.py", line 30, in <module> 
l = Lutany(675) 
File "lutany.py", line 7, in init 
self.formulab = self.formulaB 
AttributeError: Lutany instance has no attribute 'formulaB'

Answer 1

You've indented the block for the formulaB() method too much (although the edit to the question has destroyed evidence of this). Make sure that it is at the indent level directly beneath the class indent, not that of the previous method.

Answer 2

当您说“ formalaA”中的self.formulab = formulaB()时，您是说self.formulab = self.formulaB()吗？

Answer 3

You're missing parentheses here: self.formulab = self.formulaB . Should be self.formulab = self.formulaB() .