CODEWITHSUNDEEP
pythonsockets
The_Coding_Is_Now
The_Coding_Is_Now

Reputation: 35

Sockets and functions

I have a big question I couldn't get answer from the web about sockets in python. I'm making a simple client program (python) based on socket: Connecting to a server.

I would like to make a function that its purpose is just to try to connect to the server, otherwise the application will not work. Because I had trouble with "global" socket variable across the whole class, I decided to make a local socket variable inside my main and pass it through all functions.

I wanted to make sure that I understand it 100% : Should I return the socket from the function that's trying to connect to the server ( otherwise sleeps for 0.5 a second and tries again ) OR I don't need to return the socket at all and the socket variable itself will be updated ?

UPDATE

#will try to connect to the server 
def try_connecting_to_server(socket_to_server):
    connected = False
    while not connected:
        try:
            socket_to_server.connect((HOST, PORT))  # connect to the server
            connected = True
        except:
            print "couldn't connect to server, sleeping for 0.5 seconds"
            time.sleep(0.5)

    return socket_to_server

def main():
    # start the socket to the server
    socket_to_server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)  #                          setup the socket for future use
try:
    socket_to_server = try_connecting_to_server(socket_to_server)
    handle_missions(socket_to_server) # pass the socket
except:
    print "encountered an error"
finally:
    socket_to_server.sendall(PROTOCOL_CLOSE_KEY)
    socket_to_server.close()

if __name__ == "__main__":
    main()

Upvotes: 0

Views: 911

Answers (1)

Jonathon Reinhart
Jonathon Reinhart

Reputation: 137398

def try_connecting_to_server(socket_to_server):
    connected = False
    while not connected:
        try:
            socket_to_server.connect((HOST, PORT))  # connect to the server
            connected = True
        except:
            print "couldn't connect to server, sleeping for 0.5 seconds"
            time.sleep(0.5)

    return socket_to_server

There is no reason for this function to return socket_to_server.

Since a socket object is mutable, any changes to it inside the function (e.g. connecting it to a server) are visible to the function which called it.

You can verify that by making this change in main():

returned_sock = try_connecting_to_server(socket_to_server)
if returned_sock is socket_to_server:
    print "They refer to the exact same object!"

See How do I pass a variable by reference?

Upvotes: 1

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