CODEWITHSUNDEEP
pythonmodule
positivelydoped23
positivelydoped23

Reputation: 61

How do modules work in Python?

I was wondering how does a module really work in Python.For example I have this code

import requests
r = requests.get("http://www.google.com")
print r.status_code

Now according to my understanding, the requests module should have a python file which would be containing a class called "get" and within the "get" class there must be a member variable called "status_code" So when I create the object "r", I get the variable status_code for it.

However, when I looked at all the files that come in the package, I could not find any class named "get". I could however find a function called "get", under a class called "response". But since we did not create the object as an instance of the "response" class, how can we access the "get" function inside it?

I think I am missing a key concept here, can someone point it out for me please?

Thanks

Upvotes: 3

Views: 125

Answers (2)

Martijn Pieters
Martijn Pieters

Reputation: 1124488

Your understanding is not entirely correct.

The requests module is an object; .get is then an attribute lookup on that object; it has to be a callable object because you try to call it with the (...) syntax. That means it can be a class, or a function or any other object with a __call__ method.

That callable returns something; all callables do. For a class, generally an instance is returned, but for a function that can be any Python object. Whatever .get() does, it returns an object that has a .status_code attribute, or has a .__getattr__ method that returns something when called with the name status_code.

In this specific case, get() is a function, which has been imported into the requests/__init__.py package initializer module. This function, indirectly, creates a Session() instance, and calls the .request() method on that instance. That method, eventually, returns a Response instance, which does have a .status_code attribute.

Upvotes: 2

jabaldonedo
jabaldonedo

Reputation: 26582

When you import requests file __init__.pyis executed, if you examine that file in your case, you will find this line:

from .api import request, get, head, post, patch, put, delete, options

Which means that from api.py you are importing get() function:

def get(url, **kwargs):
    kwargs.setdefault('allow_redirects', True)
    return request('get', url, **kwargs)

And as you can see it calls request function from api.py that looks like:

def request(method, url, **kwargs):
    session = sessions.Session()
    return session.request(method=method, url=url, **kwargs)

That creates an object Session defined inside session.py, then calls its method request. This method will call method send() which returns a Responseobject which is defined in the class Response inside models.py (I copy the first lines):

class Response(object):
    def __init__(self):
        super(Response, self).__init__()

        self._content = False
        self._content_consumed = False

        #: Integer Code of responded HTTP Status.
        self.status_code = None
...

Here is where status_code is defined, so when you invoke r = requests.get("http://www.google.com") you are retrieving this object and then you can access to status_code

Upvotes: 4

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