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Python newbie here. I'm having problems trying to import and/or use a method from a class that I've created which I created a "/lib" directory for.

Here is my current file tree:

/tokenmgt /lib/myToken.py

From the directory:

/tokenmgt

I am running the python from the command line in this directory. I want to use the "create" method defined in my class "TokenMgr":

class TokenMgr(): """Model a Token Manager""" def __init__(self): pass def create(self, privkey, email): """<REST OF CODE HERE>"""

I'm getting these errors:

Type "help", "copyright", "credits" or "license" for more information. >>> import lib.myToken >>> from lib.myToken import create Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: cannot import name 'create' from 'lib.myToken' (C:\Users\FOO\Desktop\MyWork\dev\lib\myToken.py)

Do I need to also import the class name ("TokenMgr" defined in the .py script? I'm confused how to do this properly. Thanks

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  • possibly something like: import myToken.TokenMgr granted the other file you want to make use of this method is within the same directory level. Commented Aug 9, 2020 at 5:16
  • @FishingCode - thx. I got a little farther. But when I use the class it, it says NameError: name 'create' is not defined Commented Aug 9, 2020 at 5:24
  • I'm calling it like so - my_token = create(private_key,'[email protected]') Commented Aug 9, 2020 at 5:26
  • ah, ok. I think it has to be something like import myToken.TokenMgr as tokenMethod tokenMethod can be anything you want and then call the create like so: tokenMethod.create(). Commented Aug 9, 2020 at 5:27
  • 1
    @FishingCode You actually need to instantiate the class here. Commented Aug 9, 2020 at 5:39

2 Answers 2

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This is the proper way to import and use a class:

from lib.MyToken import TokenMgr manager = TokenMgr() manager.create(private_key,'[email protected]')

Note the second line, in which we create an instance of the class.

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1 Comment

Thank you @bensha - your reply and answer solved my immediate need to get it to work!
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The create method can be accessed only through an object. So you should import your class, create an instance and then do instance.create().. if you feel the create should not be tied to any object u can decorate it using @classmethod, so that you can access without an object..

Here are a bit of basics. Pythons classes can have three types of routines.

  1. Instance methods -> These are tied to an object, they receive self as the first argument, which is the object
  2. Class methods -> Which are common for all objects of a class, and the first argument is cls for these methods instead of self
  3. Static methods -> They are also tied to a class, but they neither receive class or object instance as their first argument. This is as good as having a standalone function, outside a class definition.

2 and 3 are achieved with @classmethod and @staticmethod decorators respectively like below:

In [6]: B.create(10) In static create method..

In [7]: class A: ...: @classmethod ...: def create(cls,x): ...: print("In create method with args {},{}".format(cls, x)) ...: ...: In [8]: A.create(10) In create method with args <class '__main__.A'>,10 In [4]: class B: ...: @staticmethod ...: def create(x): ...: print("In static create method..") ...: In [6]: B.create(10) In static create method..

In your case you can use either of them based on your requirement or create an object of the TokenManager class and then call create method like below:

tokenManager_obj = TokenManager() tokenManager_obj.create()
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2 Comments

This is all correct, but especially as the OP is a newbie, you need to give some more detail about how they would actually do this.
@alaniwi - thanks. Yes, I am trying to learn both how to import properly and use a class. So any simple example would be appreciated. thank you all

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