python OOP，访问属性

Question

Why do i get an "AttributeError: 'NewOne' object has no attribute 'self.b'" error message when i try to access the attribute 'self.b' from the NewOne class. I mean it's right there.

class NewOne(object):  
    def __init__(self):
        self.b = 'Cat' # this is what i want to access
    def child(self):
        self.c = 'kitten'
        return self.c

class FatherClass(object):
    def __init__(self, a):
        self.a = a
    def son(self):
        self.i = 'I and my father'
        return self.i
    def father(self):
        self.x = 'are one'
        return self.x
    def father_son(self):
        u = NewOne()
        k = getattr(u, 'self.b') #why does it tell me NewOne has no self.b attr
        return self.a, k()

Isn't getattr used to access a method? Why is it called getattr and not getmeth or something? Thanks

Answer 1

replace this:

k = getattr(u, 'self.b')

by this:

k = getattr(u, 'b')

or even better just do:

k = u.b

Answer 2

Youe should write

k = getattr(u, 'b')

or better

k = u.b

instead.

The name of the attribute is b , not self.b . And usually you access attributes via obj.attr -- the getattr() form is only needed if the name of the attribute is dynamic (ie not known at the time you write the code, but computed at run time).