[Tutor] Namespace Problem

[Carroll, Barry]

Bob:

Yes I did mean 'import' and yes there is more to the function.  Here is the
entire program.  

########################
import socket
import struct

# data packet flags
ABC = 1
DEF = 2
GHI = 4
JKL = 8
seq = 0

buf = 8192 # This is the max_packet_size defined in the SocketServer module
addr = ('localhost', 12345) # Host and port used by the server

def do_stuff(in_str):
    hdr = struct.pack('@2BH',ABC|DEF,seq,len(in_str))
    newstr = hdr+in_str
    if(sock.sendto(newstr,addr)):
        response = sock.recv(buf)
        flags, retseq, dlen = struct.unpack('@2BH', response[:4])
        print "flags: 0x%X, retseq: %u, dlen: %u" % (flags, retseq, dlen)
        response = response[4:]
        rsphdr=eval(response[:response.find(')')+1])
        response = response[response.find(')')+2:]
        resptupl = (rsphdr, response)
        seq += 1
    return resptupl

sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

def_msg = "===Enter message to send to server===";
print "\n",def_msg

# Send messages
while (1):
    data = raw_input('>> ')
    if not data:
        break
    else:
        print "Sending message '",data,"'"
        ret_data = do_stuff(data)
        print "Got back: ", ret_data

sock.close( )
########################

Here is a trace of program execution.  

>>>>>>>>>>>>>>>>>>>>>>>>
===Enter message to send to server===
>> send some data
Sending message ' send some data '
Traceback (most recent call last):
  File "./bgctest.py", line 40, in ?
    ret_data = do_stuff(data)
  File "./bgctest.py", line 15, in do_stuff
    hdr = struct.pack('@2BH',ABC|DEF,seq,len(in_str))
UnboundLocalError: local variable 'seq' referenced before
assignment>>>>>>>>>>>>>>>>>>>>>>>>

I can't figure it out.  

Barry

> -----Original Message-----
> From: bob [mailto:bgailer at alum.rpi.edu]
> Sent: Friday, November 04, 2005 6:32 PM
> To: Carroll, Barry; 'tutor at python.org'
> Cc: Carroll, Barry
> Subject: Re: [Tutor] Namespace Problem
> 
> At 05:47 PM 11/4/2005, Carroll, Barry wrote:
> >I have a function that makes use of several global variables:
> >
> >##########
> >Include struct
> 
> Did you mean "import"?
> 
> >ABC = 1
> >DEF = 2
> >xyz = 0
> >def do_stuff(in_str):
> >     hdr = struct.pack('@2BH',ABC|DEF,xyz,len(in_str))
> >     newstr = hdr+in_str
> 
> Works find for me. Is there anything else you are not showing us?
> 
<<snip>>