Question

I’m trying to use a global variable. I’ve declared it as global to begin with and the declare it at such at each mention, but I get a NameError after the first function completes. Here’s the code, and I think I’ve gone stare crazy but I can’t seem to find the problem.

def on_servername_insertatcursor(self, widget):
    global output  
    output = StringIO.StringIO()         
    servername = widget.get_text()
    output.write("USHARE_NAME="+servername+'\n')

def on_netif_changed(self, widget):
    netif = widget.get_active_text()
    global output
    output.write("USHARE_IFACE="+netif+'\n')

def on_port_insertatcursor(self, widget):
    global output
    port = widget.get_text()
    output.write("USHARE_PORT="+port+'\n')

def on_telprt_insertatcursor(self, widget):
    global output
    telprt = widget.get_text()
    output.write("USHARE_TELNET_PORT="+telprt+'\n')

def on_dirs_insertatcursor(self, widget):
    global output
    dirs = widget.get_text()
    output.write("USHARE_DIR="+dirs+'\n')

def on_iconv_toggled(self, widget):
    global output
    iconv = widget.get_active()
    if iconv == True:
        output.write("USHARE_OVERRIDE_ICONV_ERR="+"True"+'\n')
    else:
        output.write("USHARE_OVERRIDE_ICONV_ERR="+"False"+'\n')

def on_webif_toggled(self, widget):
    global output
    webif = widget.get_active()
    if webif == True:
        output.write("USHARE_ENABLE_WEB="+"yes"+'\n')
    else:
        output.write("USHARE_ENABLE_WEB="+"no"+'\n')

def on_telif_toggled(self, widget):
    global output
    telif = widget.get_active()
    if telif == True:
        output.write("USHARE_ENABLE_TELNET="+"yes"+'\n')
    else:
        output.write("USHARE_ENABLE_TELNET="+"no"+'\n')

def on_xbox_toggled(self, widget):
    global output
    xbox = widget.get_active()
    if xbox == True:
        output.write("USHARE_ENABLE_XBOX="+"yes"+'\n')
    else:
        output.write("USHARE_ENABLE_XBOX="+"no"+'\n')

def on_dlna_toggled(self, widget):
    global output
    dlna = widget.get_active()
    if dlna == True:
        output.write("USHARE_ENABLE_DLNA="+"yes"+'\n')
    else:
        output.write("USHARE_ENABLE_DLNA="+"no"+'\n')

def on_commit_clicked(self, widget):
    commit = output.getvalue()
    logfile = open('/home/boywithaxe/Desktop/ushare.conf','w')
    logfile.write(commit)

def on_endprogram_clicked(self, widget):
    sys.exit(0)

What’s amazing is that when insertatcursor (coming from Gtk.TextBuffer.insert_at_cursor() ) is replace with activate, the code works perfectly, except I don’t want to have the user have to press enter after every data input.

EDIT. The Traceback is as follows

Traceback (most recent call last):
File "/home/boywithaxe/Developer/Quickly/broadcast/broadcast/BroadcastWindow.py", line     58, in on_netif_changed
output.write("USHARE_IFACE="+netif+'\n')
NameError: global name 'output' is not defined

Having made the changes suggested by @jdi (Thank you btw, I see the logic behind that), the Traceback I get is as follows:

Traceback (most recent call last):
File "/home/boywithaxe/Developer/Quickly/broadcast/broadcast/BroadcastWindow.py", line 55, in on_netif_changed
OUTPUT.write("USHARE_IFACE="+netif+'\n')
NameError: global name 'OUTPUT' is not defined
Traceback (most recent call last):
File "/home/boywithaxe/Developer/Quickly/broadcast/broadcast/BroadcastWindow.py", line 72, in on_iconv_toggled
OUTPUT.write("USHARE_OVERRIDE_ICONV_ERR="+"True"+'\n')
NameError: global name 'OUTPUT' is not defined
Traceback (most recent call last):
File "/home/boywithaxe/Developer/Quickly/broadcast/broadcast/BroadcastWindow.py", line 79, in on_webif_toggled
OUTPUT.write("USHARE_ENABLE_WEB="+"yes"+'\n')
NameError: global name 'OUTPUT' is not defined
Traceback (most recent call last):
File "/home/boywithaxe/Developer/Quickly/broadcast/broadcast/BroadcastWindow.py", line 86, in on_telif_toggled
OUTPUT.write("USHARE_ENABLE_TELNET="+"yes"+'\n')
NameError: global name 'OUTPUT' is not defined
Traceback (most recent call last):
File "/home/boywithaxe/Developer/Quickly/broadcast/broadcast/BroadcastWindow.py", line 93, in on_xbox_toggled
OUTPUT.write("USHARE_ENABLE_XBOX="+"yes"+'\n')
NameError: global name 'OUTPUT' is not defined
Traceback (most recent call last):
File "/home/boywithaxe/Developer/Quickly/broadcast/broadcast/BroadcastWindow.py", line 100, in on_dlna_toggled
OUTPUT.write("USHARE_ENABLE_DLNA="+"yes"+'\n')
NameError: global name 'OUTPUT' is not defined
Traceback (most recent call last):
File "/home/boywithaxe/Developer/Quickly/broadcast/broadcast/BroadcastWindow.py", line 105, in on_commit_clicked
commit = OUTPUT.getvalue()
NameError: global name 'OUTPUT' is not defined

Answer 1

Your code example doesn’t require a global. Just remove it. The only time you need to use the global keyword in a function is if you are going to assign to it.

OUTPUT = StringIO.StringIO()         

def on_servername_insertatcursor(self, widget):
    servername = widget.get_text()
    OUTPUT.write("USHARE_NAME="+servername+'\n')

def on_netif_changed(self, widget):
    netif = widget.get_active_text()
    OUTPUT.write("USHARE_IFACE="+netif+'\n')

def on_port_insertatcursor(self, widget):
    port = widget.get_text()
    OUTPUT.write("USHARE_PORT="+port+'\n')

def on_telprt_insertatcursor(self, widget):
    telprt = widget.get_text()
    OUTPUT.write("USHARE_TELNET_PORT="+telprt+'\n')

def on_dirs_insertatcursor(self, widget):
    dirs = widget.get_text()
    OUTPUT.write("USHARE_DIR="+dirs+'\n')

def on_iconv_toggled(self, widget):
    iconv = widget.get_active()
    if iconv == True:
        OUTPUT.write("USHARE_OVERRIDE_ICONV_ERR="+"True"+'\n')
    else:
        OUTPUT.write("USHARE_OVERRIDE_ICONV_ERR="+"False"+'\n')

Even if you wanted to be able to reset your StringIO object in a function, it still wouldn’t require an assignment or global keyword:

def reset_output(self):
    OUTPUT.seek(0)
    OUTPUT.truncate()

Proof that it works

import StringIO

OUTPUT = StringIO.StringIO()         

def foo():
    OUTPUT.write('foo')

def bar():
    OUTPUT.write('bar')

def print_output():
    print OUTPUT.getvalue()

def reset_output():
    OUTPUT.seek(0)
    OUTPUT.truncate()

if __name__ == "__main__":
    foo()
    bar()
    print_output()
    reset_output()
    print_output()

Output

$ python test.py 
foobar

$