If you just try calling update
yourself, instead of passing it to FTP.storbinary
, you'll see the problem immediately:
>>> update('')
UnboundLocalError: local variable 'count' referenced before assignment
If you want to update a global variable, you have to mark it global explicitly:
def update(block):
global count
count += 1
print count
See the FAQ entry Why am I getting an UnboundLocalError when the variable has a value? and the following question What are the rules for local and global variables in Python?, and the docs on global
, for more details.
A better way to solve this would be to write a class:
class FtpHandler(object):
def __init__(self):
self.count = 0
def update(self, block):
self.count += 1
print self.count
Then, to use it, you construct an instance of the class, and pass a bound method instead of a plain function to the FTP code. For example, instead of this:
ftp = ftplib.FTP(...)
# ...
ftp.storbinary(spam, eggs, callback=update)
… do this:
myhandler = FtpHandler()
ftp = ftplib.FTP(...)
# ...
ftp.storbinary(spam, eggs, callback=myhandler.update)