Call a function from outside a class - Python

Question

Having some trouble calling stream_to_stop() from within StreamingForexPrices.. The following code gives this error:

TypeError: unbound method stream_to_stop() must be called with StreamingForexPrices instance as first argument (got int instance instead)

Can someone please help me understand? Thanks

class StreamingForexPrices(object):
 def __init__(
 self, domain, access_token,
 account_id, instruments, events_queue
 ):
 self.domain = domain
 self.access_token = access_token
 self.account_id = account_id
 self.instruments = instruments
 self.events_queue = events_queue
 def stream_to_stop(self):
 response = self.connect_to_stream()
 if response.status_code != 200:
 return
 for line in response.iter_lines(1):
 if line:
 try:
 msg = json.loads(line)
 except Exception as e:
 print "Caught exception when converting message into json\n" + str(e)
 return
 if msg.has_key("instrument") or msg.has_key("tick"):
 print msg["tick"]["ask"] - .001
 instrument = msg["tick"]["instrument"]
 time = msg["tick"]["time"]
 bid = msg["tick"]["bid"]
 ask = msg["tick"]["ask"]
 stopLoss = msg["tick"]["ask"] - .001
 tev = StopEvent(stopLoss)
 self.events_queue.put(tev)
stop = StreamingForexPrices.stream_to_stop()
print stop

My goal is to print the output of stream_to_stop.. Thanks again!

Edited indentation..

• Kivak Wolf: Not super familiar with python, but I think you're calling a class method without creating the object. try creating a StreamingForexPrices object and then calling the function?
• jonrsharpe: You aren't actually creating an instance of StreamingForexPrices. Should stream_to_stop be a @classmethod? Given that you have two methods, one of which is __init__, you might find this useful: youtube.com/watch?v=o9pEzgHorH0
• Ella Sharakanski: stream_to_stop is not a method of StreamingForexPrices. Is the indentation right? And if it's a method of StreamingForexPrices then you should call it on an instance of StreamingForexPrices, not on the class itself.
• MacD: No the indentation is not correct, I took a bunch of stuff out that wasn't needed for the question.. And that would make a lot more sense as far as not creating an instance
• MacD: @jonrsharpe - great link! Just watched the first few minutes and I definitely have my work cut out for me.. Thanks

Answer 1

domain = "www.example.com"
access_token = "ldkjflekfjelkxlk"
account_id = "account"
instruments = ["some instrument I don't how to play"]
events_queue = xxx # It sounds like an object created to handle queue
stop = StreamingForexPrices(domain, access_token, account_id, instruments, events_queue).stream_to_stop()

How to use python class

• MacD: Thanks @Shuo.. This gives me the error 'NameError: name 'domain' is not defined'
• jonrsharpe: @user2883183 well obviously you'll need to define the parameters you pass to __init__ - where were you expecting them to come from?
• MacD: Got it.. I had taken out the parameters when writing the question here. Thanks a lot guys!