Python NameError when defining class -

the below python fails reason.

import urllib.request, urllib.parse, threading  class netvend:     def blankcallback(data):         pass      def setaddress(priv):         pass      def signcommand(command):         pass      def sendcommand(command, callback=netvend.blankcallback):         return netvend.sendsignedcommand(command, netvend.signcommand(command), callback)      def sendsignedcommand(command, sig, callback=netvend.blankcallback):         fileobj = urllib.request.urlopen(netvend.commandurl, urllib.parse.urlencode({"address": netvend.eckey.getbitcoinaddress().tostring(), "command": command, "signed": sig}))         threading.thread(target=callback, args=(fileobj.read())).start() # act javascript callback.      def parseresponce(data):         ampsplit = data.split("&")         ampfirstcharsplit = ampsplit[0].split("")         if ampfirstcharsplit[0] == "s":             success = true             ampfirstcharsplit.pop(0)             commandid = ampfirstcharsplit.join("")             returnstring = ampsplit[1]         elif ampfirstcharsplit[0] == "e":             success = false             ampfirstcharsplit.pop(0)             errormessage = ampfirstcharsplit.join("")         else:             raise exception("invalid responce code. contact admin @ 8kstq@notsharingmy.info")         return {"success" : success, "commandid" : commandid, "returnstring" : returnstring, "errormessage" : errormessage}      def gerneratecommanddata(message):         return "data&" + netvend.urlencode(message)      def gerneratecommandtip(userid, usats, dataid):         return "tip&" + netvend.urlencode(userid) + "&" + netvend.urlencode(usats) + "&" + netvend.urlencode(dataid)      def commanddata(message, callback=netvend.blankcallback):         return netvend.sendcommand(netvend.gerneratecommanddata(message), callback)      def commandtip(userid, usats, dataid, callback=netvend.blankcallback):         return netvend.sendcommand(gerneratecommandtip(userid, usats, dataid), callback)      def commandtipandmessage(userid, usats, message, callback=netvend.blankcallback):         pass  netvend.commandurl = "http://ec2-54-213-176-154.us-west-2.compute.amazonaws.com/command.php" netvend.commanddata("test") 

i following error:

traceback (most recent call last):   file "c:\users\harborow\desktop\raw.py", line 17, in <module>     class netvend:   file "c:\users\harborow\desktop\raw.py", line 27, in netvend     def sendcommand(command, callback=netvend.blankcallback): nameerror: name 'netvend' not defined 

you cannot refer class name while still defining it.

the class body executed local namespace; can refer functions , attributes local names instead.

moreover, default values function keyword parameters bound @ definition time, not when method called. use none sentinel instead.

instead of:

def sendcommand(command, callback=netvend.blankcallback):     return netvend.sendsignedcommand(command, netvend.signcommand(command), callback) 

use:

def sendcommand(command, callback=none):     if callback none:         callback = netvend.blankcallback     return netvend.sendsignedcommand(command, netvend.signcommand(command), callback) 

you wanted use class factory instances instead of namespace functions. if used 1 instance (a singleton) there benefits in creating instance first.