Here is Customer class:
class Customer:
def __init__(self, timestamp, cid, item_count):
self.time_stamp = timestamp
self.customer_name = cid
self.item_count = item_count
def checkout(self, new_timestamp):
self.time_stamp = new_timestamp
def get_cus_name(self):
return self.customer_name
If I create an empty list of Customer objects like:
customers = [Customer]
And then somewhere else I try to call Customer methods in a loop like:
def checkout_customer(self, cid):
for cus in self.customers:
if cus.get_cus_name == cid:
cus.checkout(self.cur_num_customers + 7)
why do I get an error when I try to call cus.checkout? My ide tells me that it expects a Customer but got an int. Why doesn't it pass itself into the 'self' arg here?
However if I just create a Customer object and directly call its methods, it works fine:
def foo(self):
cus = Customer(1,'pop',2)
cus.checkout(23)
This is my first time learning python, and ive been stuck trying to figure out lists, and accessing its members. Perhaps my initialization of self.custormers = [Customer] is incorrect?
EDIT:
In my constructor of tester class I create an empty list like this:
self.customer = [Customer]
I am able to add customers no problem:
def add_custormer(self, customer):
self.customers.append(customer)
My problem is not adding customers, but accessing their methods once they are in a list. Doing something like this self.customers[0].checkout(1,'pop',2) gives me an error "Expected type 'Customer' got int".
I am not sure of the class where checkout_customer lives but I am assuming you declare the list self.customers somewhere in it.
self.costumers = []
If you intend to add an element Customer to the list you should use something like: self.customers.append(Customer(x,y,z)) since you want to add a new customer to the list and when doing so you are required to initialize the Customer class.
I didn't try the code but I believe something like this should work:
def foo(self):
self.customers.append(Customer(1,'pop',2))
self.checkout_customers(23)
Related
The below python class have empty dictionary as initial arguments, after calling
createAccount() outside class it successfully add data to dictionary but I can't access dictionary outside class.
What changes shall I make in the below code to access the newly created account details ?
*Please note that my error occurs in the last line of the code *
class SavingsAccount():
def __init__(self):
self.savingsAccounts = {}
def createAccount(self, name, initialDeposit):
print()
self.accountNumber = int(12345)
self.savingsAccounts[self.accountNumber] = [name, initialDeposit]
print("Account creation has been successful. Your account number is ", self.accountNumber)
SavingsAccount().createAccount(name = 'a',initialDeposit=4)
print(SavingsAccount().savingsAccounts[12345]) # getting error here
You should initialize your object using __init__,
class SavingsAccount:
def __init__(self, name, initial_deposit):
self.accountNumber = 12345
self.savingsAccounts = {self.accountNumber : [name, initial_deposit] }
print("Account creation has been successful. Your account number is ", self.accountNumber)
saving_account = SavingsAccount(name='a', initial_deposit=4)
print(saving_account.savingsAccounts)
Also, most of the Pythonistas prefer snake_casing while naming variables.
You are creating a new instance of SavingsAccount with every call. After you call to createAccount completes, that instance is garbage-collected, as there are no references to it stored anywhere.
s = SavingsAccount()
s.createAccount(name='a', initialDeposit=4)
print(s.savingsAccounts[12345])
(See Taohidul Islam's answer for how you should be defining the class, though.)
The line that gives the error does this actions:
Calls SavingsAccount.init() to create the object
Asks for the item 12345 in the dictionary (that whas just created so it's empty)
You should structure your code in a different way. You should have a list of accounts or similar that is unique, and then insert in it the accounts you create.
Must first initialize an instance of your SavingsAccount class
#initialize savings account object
s = SavingsAccount()
#call created account method
s.createAccount(name="a", initialDeposit=4)
#print the account
print(s.savingsAccounts[12345])
Although your datastructure is confusing, why not have one instance of a savings account object represent an individuals account? Then you could just assign member variables for values you want to track.
class SavingsAccount:
def __init__(self, name, initial_deposit):
self.account_name = name
self.bal = initial_deposit
def deposit(self, val):
self.bal += val
def return_account(self):
return self.__dict__
Now you can use it more simplistically
s = SavingsAccount("name", 500)
s.deposit(500)
acc = s.return_account()
print(acc)
>> {"account_name": "name", "bal": 1000}
I would like to simply make a list of kinds of coffe, but get an error stating that the list is not defined. Do I have to use self in the constructor when referencing to a classvariable?
I have tried changing the return statement to return self.coffelist.append(name), but then get another error: 'Function' object has no attribute 'append'.
class coffe:
coffelist = []
def __init__(self,name,origin,price):
self.name = name
self.origin = origin
self.price = price
return (self.coffelist.append(self.name))
def coffelist(self):
print(coffelist)
c1=coffe("blackcoffe","tanz",55)
c2=coffe("fineroasted","ken",60)
This is because you named one of your methods as coffelist.
I think this shows how to do what you want. I also modified your code to follow the PEP 8 - Style Guide for Python Code and corrected some misspelled words.
class Coffee: # Class names should Capitalized.
coffeelist = [] # Class attribute to track instance names.
def __init__(self,name,origin,price):
self.name = name
self.origin = origin
self.price = price
self.coffeelist.append(self.name)
def print_coffeelist(self):
print(self.coffeelist)
c1 = Coffee("blackcoffee", "tanz", 55)
c1.print_coffeelist() # -> ['blackcoffee']
c2 = Coffee("fineroasted", "ken", 60)
c1.print_coffeelist() # -> ['blackcoffee', 'fineroasted']
# Can also access attribute directly through the class:
print(Coffee.coffeelist) # -> ['blackcoffee', 'fineroasted']
yes thanks that's exactly what I wanted!
I wasnt sure.. I thought you could do 2 things simultaneously in the return statement, both return append. I guess allot of times python is very flexible and sometimes not. thanks
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
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:
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).
I have a simple class that stores simple data. The class is as follows.
class DataFormater:
def __init__(self, N, P, K, price):
self.N = N
self.P = P
self.K = K
self.price = price
The code that calls this class is
from DataFormater import DataFormater
#global variables
ObjectList = [0,1,2,3,4,5,6,7,8,9,10,
11,12,13,14,15,16,17,18,19,20,
21,22,23,24,25,26,27,28,29,30,
31,32,33,34,35,36,37,38,39,40,
41,42,43,44,45,46,47,48,49,50]
ObjectListCounter = 0
# main
print "enter you N-P-K values, followed by a coma, then the price"
print "example ----> 5 5 5 %50 "
print "return as many values as you want to sort, then enter, 'done!' when done."
while True:
RawData = raw_input()
if RawData == 'done!':
break
else:
ObjectList[ObjectListCounter] = DataFormater
ObjectList[ObjectListCounter].N = int(RawData[0])
# very simple test way of putting first indice in ObjectList[ObjectListCounter].N
ObjectListCounter += 1
print ObjectList[0].N
print ObjectList[1].N
My idea is that ObjectList[0] would create that object '1' that I could call with 1.N
But, when I call these, it seems that I have overwritten the previous instances.
this is what prints...
return as many values as you want to sort, then enter, 'done!' when done.
12
1
done!
1
1
Thanks so much! And I know that my post is messy, I don't exactly know how to make it more "pretty"
So, it looks like you are assigning the actual class (instead of an instance of the class) in your loop. Where you do this:
ObjectList[ObjectListCounter] = DataFormater
I think what you actually want is this
ObjectList[ObjectListCounter] = DataFormater(...insert args here....)
EDIT to address the comments:
Your class init method looks like this:
def __init__(self, N, P, K, price):
That means that to create an instance of your class, it would look like this:
my_formater = DataFormater(1, 2, 3, 4)
You would then be able to access my_formater.N which would have a value of 1.
What you are trying to do instead is access a CLASS level attribute, DataFormater.N. This is generally used in situations where you have a constant variable that does not change between instances of the class. For example:
class DataFormater():
CONSTANT_THING = 'my thing that is always the same for every instance'
You would then be able to access that variable directly from the class, like this:
DataFormater.CONSTANT_THING
I hope that clears things up.
I have a class `Collection' that looks like this:
class Collection():
def __init__(self, db, collection_name):
self.db = db
self.collection_name = collection_name
if not hasattr(self.__class__, 'client'):
self.__class__.client = MongoClient()
self.data_base = getattr(self.client, self.db)
self.collection = getattr(self.data_base, self.collection_name)
def getCollectionKeys(self):
....etc.
I cleverly created a function to create a dictionary of class instances as follows:
def getCollections():
collections_dict = {}
for i in range(len(db_collection_names)):
collections_dict[db_collection_names[i]] = Collection(database_name, db_collection_names[i])
return collections_dict
it works. however, whenever I want to access a class instance, I have to go through the dictionary:
agents_keys = collections_dict['agents'].getCollectionKeys()
I would love to just write:
agents_keys = agents.getCollectionKeys()
Is there a simple way to get those instances "out" of the dict?
You can get a reference to items in a vanilla python dictionary using a generator object in a for loop, or by using a list expression.
agent_keys = [x.getCollectionKeys() for x in collections_dict.values()]
or this
agent_keys = []
for name in db_collection_names:
#do something with individual item
#there could also be some logic here about which keys to append
agent_keys.append(collections_dict[name].getCollectionKeys())
#now agent_keys is full of all the keys
My mental model of how objects are interacted with in python. Feel free to edit if you actually know how it works.
You cannot "take" items of the dictionary per say unless you call the del operator which removes the association of a variable name (that is what you type in the editor like "foo" and "bar") with an object ( the actual collections of bits in the program your machine sees). What you can do is get a reference to the object, which in python is a symbol that for all your intents and purposes is the object you want.
The dictionary just holds a bunch of references to your database objects.
The expression collections_dict['agents'] is equivalent to your original database object that you put into the dictionary like this
collections_dict['agents'] = my_particular_object