sub-attribute of attribute in python

Question

Similar question to this, I was wondering what is the right/common way to implement attribute of an attribute in python. Or I am wrong already with such a thought. Here are the examples:

method 1

It's obvious that it doesn't allow self.father.height

class household:
    def __init__(self, address, name0, height0, name1,height1 ):
        self.address = address
        self.father.name = name0
        self.father.height = height0
        self.mother.name = name1
        self.mother.height = height1

household("198 Ave", "John", 6.4, "Jean",5.2)

output:
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-180-09f6784cb40e> in <module>
----> 1 household("198 Ave", "John", 6.4, "Jean",5.2)

<ipython-input-179-9ccb52cdb476> in __init__(self, address, name0, height0, name1, height1)
      2     def __init__(self, address, name0, height0, name1,height1 ):
      3         self.address = address
----> 4         self.father.name = name0
      5         self.father.height = height0
      6         self.mother.name = name1

AttributeError: 'household' object has no attribute 'father'

method 2

It works well by using a dictionary without the attribute of an attribute, but I tend to use method 1 although it does not work for some reason.

class household:
    def __init__(self, address, name0, height0, name1,height1 ):
        self.address = address
        self.father = {"name":name0,"height":height0}
        self.mother = {"name":name1,"height":height1}

household("198 Ave", "John", 6.4, "Jean",5.2)

You can read about Classes and Object Oriented programming in python, will help you in this situations: docs.python.org/3/tutorial/classes.html — Damião Martins
– Damião Martins, Commented Apr 1, 2021 at 23:47
maybe, create a parent class and pass those object in a list and save the list in attibute name parent — sahasrara62
– sahasrara62, Commented Apr 2, 2021 at 0:02

user14935952 · Accepted Answer · 2021-04-02 03:38:41Z

1

what you need to do is that you first need to initialise self.father and then use self.father.name.

You should also read more about OOP from the python documentatoion

answered Apr 2, 2021 at 3:38

user14935952

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Comments

bb1 · Accepted Answer · 2021-04-02 04:49:22Z

1

It seems that you can get something close to what you intended using namedtuple:

from collections import namedtuple

class household:
    def __init__(self, address, name0, height0, name1, height1 ):
        self.address = address
        Parent = namedtuple('Parent', ['name', 'height'])
        self.father = Parent(name0, height0)
        self.mother = Parent(name1, height1)

Example:

h = household("198 Ave", "John", 6.4, "Jean",5.2)
print(h.father.name, h.father.height)

It gives:

John 6.4

edited Apr 2, 2021 at 4:49

answered Apr 2, 2021 at 3:33

bb1

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Comments

Albert G Lieu · Accepted Answer · 2021-04-02 20:04:54Z

1

I don't know which method is the typical/common way to implement it. But certainly, we can get method 1 to work. @angadsinghbedi is right, we can initialise self.father as an valid object with type("",(),{}). For more details about creating an empty object, see here

class household:
    def __init__(self, address, name0, height0, name1,height1 ):
        self.address = address
        self.father = type("person", (),{})()
        self.father.name = name0
        self.father.height = height0
        self.mother = type("person", (), {})()
        self.mother.name = name1
        self.mother.height = height1

house0 = household("198 Ave", "John", 6.4, "Jean",5.2)
house0.father.name
# John

edited Apr 2, 2021 at 20:04

answered Apr 2, 2021 at 17:30

Albert G Lieu

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Comments

Prune · Accepted Answer · 2021-04-01 23:43:23Z

0

Method 1 doesn't work for exactly the reason the error message give you: you cannot create a sub-attribute for an attribute that doesn't exist. You would have to initialize self.father to something with a compatible structure; then your could assign to the child attributes.

Assigning the dict is a very good way to accomplish your desired result.

If I were to implement this, I would take the name/height pairs as a list or tuple of entries for later expansion. Some people have one parent; others have more than two.

household("198 Ave", [("John", 6.4), ("Jean",5.2)] )

answered Apr 1, 2021 at 23:43

Prune

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1 Comment

Albert G Lieu Over a year ago

thank you very much for sharing your knowledge

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