RE: Why is try...except in my code not working (gzip/text files) ?

[Barak, Ron]

Thanks Gabriel,
Okay, I get it: I was under the impression that the format check would be done on the open.
Bye,
Ron.

-----Original Message-----
From: Gabriel Genellina [mailto:gagsl-py2@yahoo.com.a r]
Sent: Thursday, November 20, 2008 02:06
To: python-list@python.org
Subject: Re: Why is try...except in my code not working (gzip/text files) ?

En Wed, 19 Nov 2008 13:25:03 -0200, Barak, Ron <Ron.Barak@lsi. com>
escribió:

I need to read a file that is either a gzip or a text file (on both
*nix and Windows).
Since I didn't find a way to determine a file type, I thought of using
the following:
>
import gzip
>
FILE = "../dpm/save_state-ssp8400-F0023209_080723-110131/top.1"
#FILE =
"../dpm/save_state-ssp8400-F0023209_080723-110131/var/log/sac.log.0.gz"
>
try:
file = gzip.GzipFile(F ILE, "r") except IOError:
file = open(FILE, "r")
>
print file.read()
>
>
Strangely, when FILE is a gzip file, all is fine.
But, when FILE is a text file (as in the above code), I get the
following:
>
$ python ./gzip_try.py
Traceback (most recent call last):
File "./gzip_try.py", line 11, in <module>
print file.read() <<<============ =======
File "c:\Python25\li b\gzip.py", line 220, in read
self._read(read size)
File "c:\Python25\li b\gzip.py", line 263, in _read
self._read_gzip _header()
File "c:\Python25\li b\gzip.py", line 164, in _read_gzip_head er
raise IOError, 'Not a gzipped file'
IOError: Not a gzipped file
>
Can you explain why the try...except in my code does not work ?
Or, back to my original problem: how do I deal with a file whether
it's a text file or a gzip file ?

Note *where* the exception is raised. Until something is actually read, no check is made for the file format.

--
Gabriel Genellina