Question

I am trying to write a basic chat client in Python for a project and have completed the task, easy. However when I handed it in they asked if I could get it to accept user input while checking for messages (an extra unmarked task for people who complete work early).

I assume this is something to do with threading, so I tried creating a thread for accepting user input and one for checking for messages, however it would appear that the raw_input stops the other thread.

How would I do this in python? Perhaps I have misunderstood how threading works? – Python Noob

Second try:

#Update last connection
s[user] = str(time.time());

#Start chat server
class chatServer ( threading.Thread ):
  def __init__ (self, channel):
    self.channel = channel
    self.lastMessage = ""
    threading.Thread.__init__ ( self ) #Pass to thread constructor

  def messageOut ( self ):
    while 1:
      print "Asking for input"
      message = raw_input("Message: ");
      s[self.channel] = message;
      time.sleep(1)

  def messageIn ( self ):
      while 1:
        print "Checking for new messages"
        if s[self.channel]!=self.lastMessage:
          print s[self.channel]
          self.lastMessage = s[self.channel]
        time.sleep(1)

print "Welcome " + user + " type to send a message"
chatServer("channel1").messageIn()
chatServer("channel1").messageOut()

---

First try:

#Start chat server
class chatServer ( threading.Thread ):
  def __init__ (self, user, channel, server):
    self.channel = channel
    self.lastMessage = ""
    self.user = user
    self.s = server
    threading.Thread.__init__ ( self ) #Pass to thread constructor

  def start ( self ):  
    print "Welcome " + self.user + " type to send a message"
    self.messageIn()
    self.messageOut()

  def messageOut ( self ):
    while 1:
      message = raw_input("Message: ");
      s['message'] = message;
      time.sleep(1)

  def messageIn ( self ):
      while 1:
        print "Checking for new messages"
        if s[self.channel]!=self.lastMessage:
          print s[self.channel]
          lastMessage = s[self.channel]
        time.sleep(1)

chatServer(user, "channel1", server).start()

Many thanks for your time

P.s. server is a simple class that gets/puts messages it is given

P.p.s This is not homework, more for my personal interest

Answer 1

Actually you are creating only one thread, reading and posting a single message in a sequential way.

You have to create two threads that read and write messages and are independent from each other. The real problem is synchronization between the two and the sharing of resources in common.