Calling attribute of class via for loop causes an error

Question

The code below

class attsClass():
    def __init__(self,aw,ax,ay,az):
        self.aw = aw
        self.ax = ax
        self.ay = ay
        self.az = az
ac = attsClass('W','X','Y','Z')
ac.ax

here I will get the result which is 'X',but if i call like how i did below we get an error

att_names = ['aw','ax','ay','az']
for att in att_names:
    print(ac.att)

here I can't access the attribute

only with this can I access it

att_names = ['ax','ay','az']
for att in att_names:
    print(att, getattr(ac, att))

can someone explain why?

Anonymous · Accepted Answer · 2019-11-14 15:14:21Z

4

Your first example gets the att attribute of ac, which doesn't exist. Variables are not used to resolve attribute names.

When you call getattr, you're passing the variable to a Python function that is able to dynamically read attributes. Since the variable is an argument here, it is resolved.

answered Nov 14, 2019 at 15:14

Anonymous

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