How to initialize class with empty dictionary - Python

Question

Apologies if the question is amateurish, I'm new to classes/objects. I've looked through other Stack posts, and haven't gotten a clear answer to my question.

I want to initialize a class with an empty dictionary, and then add the keys/values to the dictionary. How would I do that?

Here is what I have now:

class Network(object):
    
    self.dict = {}

    def __init__(self, key, value):
        """
        Initializes key and value of dictionary
        """
        self.key = key
        self.value = value   
        
    def add_key(key):
        """
        Should add the key to the dictionary if it doesn't exist
        """
        #if the key is not in the dictionary, add the key, and a value which is an empty list
        if key not in self.dict:
            self[key] = []

How would Python know that the key and value that I initialize are elements of the empty dictionary dict I created?

EDIT: I updated the code according to Ghost Ops suggestion, but receiving an attribute error when I try to test it.

class Network(object):
    

    def __init__(self, key, value):
        """
        Initializes key and value of dictionary
        """
        self.dicts = {}
        self.key = key
        self.value = value   
        
    def add_key(key):
        """
        Should add the key to the dictionary if it doesn't exist
        """
        #if the key is not in the dictionary, add the key, and a value which is an empty list
        if key not in self.dicts:
            self[key] = []
       
        # to test if the code returns correctly:
        def get_dicts(self):
            return self.dicts

test_dic = {13: [1, 2, 3], 14:[4, 5]}
print(test_dic.get_dicts())

The error: 'dict' object has no attribute 'get_dicts'

Am I perhaps testing the code wrong?/ Apologies, I am very new to this

you can put the self.dict = {} line into the __init__ function so that for every initiation, it creates a new dictionary and also, name the dictionary with an another name like self._dict not dict — Ghost Ops
– Ghost Ops, Commented Nov 6, 2021 at 13:49

nagyl · Accepted Answer · 2021-11-06 13:52:10Z

2

You could inherit your class from dict, basically your class will act as a dictionary too. Your add key method would still work perfectly fine, just change self.dict to self.keys() to get all existing keys back. Key, and Value variables are unnecessary.

class Network(dict):

    def __init__(self, key, value):
        """ Initializes superclass """
        super().__init__()  
        
    def add_key(key):
        """ Should add the key to the dictionary if it doesn't exist """
        if key not in self.keys():
            self[key] = []

answered Nov 6, 2021 at 13:52

nagyl

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