Question

Hello I am trying to port some C code to python. I haven’t used python in a few months so feel a bit rusty.

Wondering how I can do this. I need to be able to use the send value of the sock object in createConnection function with out making the sock object global.

any ideas?

*cheers

Example code

def createConnection(host, port, tcpTimeout):
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP)
    sock.connect((host, port))
    return sock

def useConnectionOne():
    sock = createConnection("<Some IP>", <Some Port>, 5)
    sock.send("Hello world")

def useConnectionTwo():
    sock = createConnection("<Some IP>", <Some Port>, 5)
    sock.send("Hello again world")

Answer 1

You either need to make the socket objects global so they can be re-used, or attach them to some other object / container to keep track of them. You could do something like this:

Connections = {}
Connections['host1'] = createConnection("<Some IP>", <Some Port>, 5)
Connections['host2'] = createConnection("<Some Other IP>", <Some Port>, 5)

Then you can send with:

Connections['host1'].send("Hello World")

Without some outer container though, your socket objects leave scope and are garbage collected when the function that creates them returns.

If I misunderstand you somehow, and you want a single connection object and the ability write two methods that use it separately, create a class that contains the connection:

class ConnManager(object):
  def __init__(self, host, port, timeout)
    self._conn = socket.socket(socket.AF_INET, socket.SOCK_STREAM, socket.IPPROTO_TCP)
    self._conn.connect((host, port))

  def sendOne(self, data):
    self._conn.send(data)

  def sendTwo(self, data):
    self._conn.send(data)

Hopefully that gives you an idea you can build from.