Python: Class definition without arguments

Question

Sorry for the noob question about classes. I'm trying to assign a soap client to a variable inside a class function and then access that variable in other class functions. I don't have any arguments to pass to the setup_client() function.

In the following example code, how do I make self.client accessible outside setup_client() so that I can use it in use_client(), and ditto making self.response available outside use_client()

class soap_call(self):
    def __init__(self):
        # What goes here?
        self.client = # what?
        self.response = # what?

    def setup_client(self):
        credentials = {'username': 'stuff', 'password': 'stuff'}
        url = 'stuff'
        t = HttpAuthenticated(**credentials)
        self.client = suds.client.Client(url, transport=t)

    def use_client(self):
        self.response = self.client.service.whatever
        print self.response

I quickly realized that if I add an optional client argument (self, client=None) to the class definition and include self.client = client, then I get a None type error when trying to use it in my functions.

I realize I just have a lack of understanding of classes. I've done some general reading up on classes but haven't come across any specific examples that describe what I'm dealing with.

Is the use of self as the base class for soap_call a typo? — chepner
– chepner, Commented May 16, 2015 at 18:45
@chepner No, it's jut my general lack of understanding, and that my IDE automatically added (self) to soap_call. — AutomaticStatic
– AutomaticStatic, Commented May 16, 2015 at 18:49

Lim H. · Accepted Answer · 2015-05-16 18:49:08Z

2

I'd go with None in both cases because logically speaking, none of them exists at the time of object instantiation. It also allows you to do some sanity checking of your logic, e.g.

class SoapCall(object):
    def __init__(self):
        self.client = None
        self.response = None

    def setup_client(self):
        credentials = {'username': 'stuff', 'password': 'stuff'}
        url = 'stuff'
        t = HttpAuthenticated(**credentials)
        if self.client is None:
            self.client = suds.client.Client(url, transport=t)

    def use_client(self):
        if self.client is None:
            self.client = self.setup_client()

        self.response = self.client.service.whatever
        print self.response

answered May 16, 2015 at 18:49

Lim H.

10.1k9 gold badges51 silver badges76 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

AutomaticStatic Over a year ago

Incidentally, I was calling my functions incorrectly, but thank you for this. It was very helpful.

chepner · Accepted Answer · 2015-05-16 18:44:08Z

0

It's fine to leave the client unspecified when you first create the instance, but then you need to be sure to call setup_client before you call use_client.

answered May 16, 2015 at 18:44

chepner

538k77 gold badges594 silver badges746 bronze badges

2 Comments

AutomaticStatic Over a year ago

I tried that, which is the problem. self.client is unavailable to use_client in the current code.

chepner Over a year ago

Yes, which is why I said you have to call setup_client before you call use_client. What does it mean to call use_client before you have client defined?

Collectives™ on Stack Overflow

Python: Class definition without arguments

2 Answers 2

1 Comment

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related