Question

I wanted to run a certain function as a thread, but I get

SyntaxError: non-keyword arg after keyword arg

And I do not understand why :

#!/usr/bin/env python
import sys
import arduinoReadThread
import arduinoWriteThread
import socket
import thread

bolt = 0
socketArray=list()
HOST ="localhost"
PORT1 =50000
PORT2 =50001

def readAndParseArgv():
    s=socket.socket(socket.AF_INET, socket.SOCK_STREAM ) #create an INET, STREAMing socket
    s.bind((HOST,PORT1)) #bind to that port
    print "test"
    s.listen(2) #listen for user input and accept 1 connection at a time.
    socketArray.append(s)
    s2=socket.socket(socket.AF_INET, socket.SOCK_STREAM ) #create an INET, STREAMing socket
    s2.bind((HOST,PORT2)) #bind to that port
    print "test"
    s2.listen(2) #listen for user input and accept 1 connection at a time.
    socketArray.append(s2)

def socketFunctionWrite1():
    print threadName
    client, address = s1.accept()
    while(bolt == 0):
        print "Writing connections"
        if len(s1ToWriteList) > 0:
            client.send(s1ToWriteList.pop(0))

def socketFunctionRead1():
    client, address = s2.accept()
    while(bolt == 0):
        f = client.recv(1024)
        print "reading connection"
        s1ToWriteList.append(f)
        print len(s1ToWriteList)

def socketFunctionWrite2():
    client, address = s2.accept()
    while(bolt == 0):
        print "Writing connections"
        if len(s2ToWriteList) > 0:
            client.send(s2ToWriteList.pop(0))

def socketFunctionRead2():
    client, address = s1.accept()
    while(bolt == 0):
        f = client.recv(1024)
        print "reading connection"
        s2ToWriteList.append(f)
        print len(s2ToWriteList)

def shutDown():
    test = raw_input("Quit ?")
    if(test =="y"):
        bolt = 1
    else:
        shutDown()

thread.start_new_thread(target=socketFunctionRead1,())
thread.start_new_thread(target=socketFunctionWrite1,())
thread.start_new_thread(target=socketFunctionRead2,())
thread.start_new_thread(target=socketFunctionWrite2,())

readAndParseArgv()
spreadSockets()

I want to open these sockets as threads. I do not get why I get the non-keyword error, as the function I want to run as a thread is socketFunctionRead1

error :

  File "pythonbis.py", line 79
    thread.start_new_thread(target=socketFunctionRead1,())
SyntaxError: non-keyword arg after keyword arg

Answer 1

The docs say the the signature for the thread.start_new_thread call is:

thread.start_new_thread(function, args[, kwargs])

The way you are calling it is:

thread.start_new_thread(target=socketFunctionRead1,())

As you can see you are passing a named (keyword) argument before the non-named one: you are saying target=socket... before ().

EDIT: just to clarify. The solution is either to remove the keyword to the first argument or to add it to the second.

HTH!