CODEWITHSUNDEEP
pythonclassvariablesscope
user4652667
user4652667

Reputation:

How to acces class variables outside class in python

I am new to python and this is my first program in python i want to know how to access class variables outside class.I have a code which throws some error

from xxxxxxx import Products

class AccessKey(object):
    def key(self):
        self.products = Products(
           api_key = "xxxxxxxxxxxxxxxxxxxxxx",
           api_secret = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
        )

class Data(AccessKey):
    def Print(self):
        products.products_field( "search", "Samsung Galaxy" )
        results = products.get_products()
        print "Results of query:\n", results

data = Data()
data.Print()

The above program throws following error

Traceback (most recent call last):
  File "framework.py", line 10, in <module>
    class Data(AccessKey):
  File "framework.py", line 13, in Data
    results = products.get_products()
NameError: name 'products' is not defined

Upvotes: 0

Views: 6347

Answers (2)

Haleemur Ali
Haleemur Ali

Reputation: 28303

the Class Data inherits from AccessKey. So the class attribute products is available to Data, however, you need to access it through

self.products.products_field(...) instead of products.products_field(...). similarly, it should be results = self.products.get_products()

But note that, the instance attribute products is only set when the method key is called, so you will get NameError until the key method is called, i.e.

data = Data()
data.key()
data.Print()

Also, in python getters and setters are discouraged, and a lot of stress is placed on code formatting guidelines. In your code the class methods should be lower case, but because print would shadow a reserverd word, something like print_ would be preferable.

Upvotes: 0

WakkaDojo
WakkaDojo

Reputation: 431

First of all, you need to call the products field as self.products. (etc)

It looks like you don't necessarily instantiate "products" before you call it. If you want to make sure it's instantiated, then you need to have products be set in the constructor of the parent class (AccessKey)

A simplified example would be:

class A (object):
    def __init__ (self):
        self.x = 1

class B (A):
    def get (self):
        return self.x

b = B ()
print (b.get ())

Basically, you would have to add the following constructor to your first class

class AccessKey(object):
    def __init__(self):
        self.products = Products (X, Y) # or whatever you want to initialize it to
    # the rest of your code below

Or, you can be even better and create a set_product function:

# inside of the parent class
    def set_product (self, X, Y):
        try:
            self.products.product_field (X, Y)
        except NameError:
            self.products = Product (X, Y)

Upvotes: 2

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