[Tutor] GzipFile has no attribute '__exit__'

[Kent Johnson]

On Mon, Nov 16, 2009 at 5:58 AM, Stephen Nelson-Smith
<sanelson at gmail.com> wrote:
> I'm trying to write a gzipped file on the fly:
>
> merged_log = merge(*logs)
>
> with gzip.open('/tmp/merged_log.gz', 'w') as output:
>    for stamp, line in merged_log:
>        output.write(line)
>
> But I'm getting:
>
> Traceback (most recent call last):
>  File "./magpie.py", line 72, in <module>
>    with gzip.open('/tmp/merged_log.gz', 'w') as output:
> AttributeError: GzipFile instance has no attribute '__exit__'
>
> What am I doing wrong, and how do I put it right?

gzip.open() doesn't support the context manager protocol needed for it
to be used in a 'with' statement. Just do this old-style:

output = gzip.open('/tmp/merged_log.gz', 'w')
try:
   for stamp, line in merged_log:
       output.write(line)
finally:
  output.close()

See PEP 343 this explanation of context managers if you want to know
why you got this specific error:
effbot.org/zone/python-with-statement.htm
http://www.python.org/dev/peps/pep-0343/

Kent