CODEWITHSUNDEEP
pythonclass-variables
Ahmed Younes
Ahmed Younes

Reputation: 1134

Class Variable NameError not defined python

In this example, it's working hotels as a class variable no NameError

class Hotel():
    """""""""
    this is hotel class file
    """
    hotels = []
    def __init__(self,number,hotel_name,city,total_number,empty_rooms):
        self.number = number
        self.hotel_name = hotel_name
        self.city = city
        self.total_number = total_number
        self.empty_rooms = empty_rooms

        Hotel.hotels.append([number,hotel_name,city,total_number,empty_rooms])

    def list_hotels_in_city(self,city):
        for i in hotels:
            if city in i:
                print "In ",city,": ",i[1],"hotel, available rooms :",i[4]

In the following example its not working 

from twilio.rest import Client


class Notifications():
    customers = []

    def __init__(self,customer_name,number,message):
        self.customer_name = customer_name
        self.number = number
        self.message = message
        Notifications.customers.append([customer_name,number,message])

    def send_text_message(self,customer_name):
        for i in customers:
            print "triggeredb"

inst = Notifications("ahmed","+00000000000","messagesample")
print "instance : ",inst.customers
inst.send_text_message("ahmed")

NameError: global name 'customers' is not defined

Update

for first example nothing called to show error but issue solved for second example Thanks Tom Dalton , scharette and James

Upvotes: 1

Views: 1631

Answers (2)

James
James

Reputation: 3411

I think it's very likely that when you ran your first example, you had a variable called hotels in your global (interpreter) scope. Thats why it's working. If I copy paste your example into my interpreter it fails with the same error message as your second code sample.

If your send_text_message function only accesses class variables (no instance variables) I would recommend making it a class method like this : 

@classmethod
def send_text_message(cls, customer_name):
    for i in cls.customers:
        print "triggeredb"

That way you can access the class variables using the cls variable and won't have to repeat the class name in your function (which is nice, as if you change the class name - you won't have to go hunting through your code for repetitions).

Upvotes: 1

scharette
scharette

Reputation: 10017

As I said in my comment, When you call for i in customers:, customers is not in scope of that function.

I just wanted to add also, that you use 

 Notifications.customers.append([customer_name,number,message])

but you also declare 

customers = []

Note that the former is a class variable and will share the variable among Notifications instances. The latter represent an instance variable. If your goal is to have a customers list for every specific object, you should use self.customers.

So basically,

You want shared list between objects ?

for i in Notifications.customers:

You want specific list for every object ?

for i in self.customers:

Upvotes: 1

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