Use string to get attribute value python

Question

I have this :

class A:
    def __getattr__(self, name):
        if name == 'a'
             return 'this'
        else:
             return 'that'

I would like to create another class that use 'class A' and use a string as the future attributes of 'A' like this:

class B:
    def use_a(self, attributes='a'):
         a = A().attributes
         return a

I would like that the method use_a(class B) return 'this' if i set attributes to 'a', but it doesn't work and returns 'that'. But i try to do a gettattr it doesn't work either. How can I do that ? Thanks a lot

can you make the program more clearer and explained?

user13747387
– user13747387

2020-06-19 16:10:55 +00:00
Commented Jun 19, 2020 at 16:10 — user13747387
– user13747387, Commented Jun 19, 2020 at 16:10

chepner · Accepted Answer · 2020-06-19 16:11:37Z

1

__getattr__ is called if A().a doesn't exist. You still need to use getattr if the attribute itself is a variable.

def use_a(self, attribute='a'):
    a = getattr(A(), attribute)
    return a

answered Jun 19, 2020 at 16:11

chepner

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2 Comments

chepner Over a year ago

a is an attribute, attribute is not. attribute is a variable whose value is the name of an attribute.

chepner Over a year ago

That is, A().x is equivalent to getattr(A(), 'x'), not getattr(A(), x).

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