Create object from class in separate file

Question

I have done several tutorials on Python and I know how to define classes, but I don't know how to use them. For example I create the following file (car.py):

class Car(object):
    condition = 'New'
    def __init__(self,brand,model,color):
        self.brand = brand
        self.model = model
        self.color = color

    def drive(self):
        self.condition = 'Used'

Then I create another file (Mercedes.py), where I want to create an object Mercedes from the class Car:

Mercedes = Car('Mercedes', 'S Class', 'Red')

, but I get an error:

NameError: name 'Car' is not defined

If I create an instance (object) in the same file where I created it (car), I have no problems:

class Car(object):
    condition = 'New'
    def __init__(self,brand,model,color):
        self.brand = brand
        self.model = model
        self.color = color

    def drive(self):
        self.condition = 'Used'

Mercedes = Car('Mercedes', 'S Class', 'Red')

print (Mercedes.color)

Which prints:

Red

So the question is: How can I create an object from a class from different file in the same package (folder)?

Do you realise that `condition` is a *class attribute*, shared by all instances? — jonrsharpe, Apr 23 '14 at 08:08
@jonrsharpe,In order to be separate for each object, I should rename it to self.condition? — Trenera, Apr 23 '14 at 08:23
Yes, set it as `self.condition = 'New'` *inside* `__init__`. — jonrsharpe, Apr 23 '14 at 09:10

score 103 · Accepted Answer · answered Apr 23 '14 at 08:04

103

In your Mercedes.py, you should import the car.py file as follows (as long as the two files are in the same directory):

import car

Then you can do:

Mercedes = car.Car('Mercedes', 'S Class', 'Red')  #note the necessary 'car.'

Alternatively, you could do

from car import Car

Mercedes = Car('Mercedes', 'S Class', 'Red')      #no need of 'car.' anymore

answered Apr 23 '14 at 08:04

sshashank124

31,495
9
67
76

Thanks, I will accept the answer after I am allowed to (in 10 min) – Trenera Apr 23 '14 at 08:08
1

what if they are _not_ in the same directory? thanks! – Jakob Ryden Sep 01 '17 at 12:19
When they are in different directory, you can refer this answer: https://stackoverflow.com/questions/13598958/import-modules-from-different-folders/13599005 – Puneeth G R Oct 11 '21 at 09:37

score 1 · Answer 2 · answered Dec 07 '16 at 13:27

1

Simply use the import command in your Mercedes file. There's a good intro about importing in Python in here

answered Dec 07 '16 at 13:27

Oren T

11
3

score 1 · Answer 3 · answered Nov 26 '20 at 00:25

1

Mercedes.py:

from car import Car

This imports the Car class from car.py To use it:

Mercedes=Car('Mercedes', 'S Class', 'Red')

answered Nov 26 '20 at 00:25

Ishan Roychowdhury

39
7

Create object from class in separate file

3 Answers3

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