Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From: Ganesh Pal <ganesh1pal@gmail.com>
Newsgroups: comp.lang.python
Subject: Re: usage of try except for review.
Date: Mon, 29 Feb 2016 15:33:18 +0530
Lines: 117
Message-ID: <mailman.5.1456740206.20602.python-list@python.org>
References: <CACT3xuWm56OE7LpR8kBLfWfkDoU18sPcN5DRiXjr=68+Kywo8Q@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
In-Reply-To: <CACT3xuWm56OE7LpR8kBLfWfkDoU18sPcN5DRiXjr=68+Kywo8Q@mail.gmail.com>
Precedence: list
Xref: csiph.com comp.lang.python:103699

Iam really sorry , I will have to resend my question again , because
the earlier post had mistakes and formatting was bad , so apologies
for top posting  will try to avoid such mistakes in future.


Iam on python 2.6 and Linux , need your suggestion on the usage of try
and except in this program

#!/usr/bin/env python


"""
"""
import os
import shlex
import subprocess
import sys
import time
import logging
import run
import pdb

def run_cmd_and_verify(cmd, timeout=3D1000):

    try:
        out, err, ret =3D run(cmd, timeout=3Dtimeout)
        assert ret =3D=3D0,"ERROR (ret %d): " \
                " \nout: %s\nerr: %s\n" % (ret, out, err)
    except Exception as e:
        logging.error("Failed to run %s got %s" % (cmd, e))
        return False
    return True

def run_test():
    """
    Mount

    """
    pdb.set_trace()

    for cmd in ["mount /nfs_mount1", "mount /cifs_mount1"]:
        try:
            if not run_cmd_and_verify(cmd, timeout=3D3600):
                return False
        except:
           logging.error("Some meaningful message")
    logging.info("Setup and Creation ....Done !!!")
    #
    cmd =3D "run_scan"
    out, err, ret =3D run(cmd)

    for cmd in ["create_data.py -nfs ",
                "validate.py -30 "]:
        try:
            if not run_cmd_and_verify(cmd, timeout=3D3600):
               return False
        except:
            logging.error("some meaningful message")
            return False
    logging.info("Mount IS START.....Done !!!")

def main():

    if not run_test():
        sys.exit("Exiting Main")

if __name__ =3D=3D '__main__':
    main()

Question 1:

(a)  Have I used try and expect block correctly  ?  in run_test()  I
have  expect  block which displays some error message  instead of pass
, is it fine ?

 (b)  Have I returned True and  False correctly , looks fine for me

    try:
        if not run_cmd_and_verify(cmd, timeout=3D3600):
                return False
    except:
           logging.error("inside except")
           return False

Question 2.

(a) If a failure=E2=80=99s are encountered  the error by assert condition t=
he
errors are now displayed on the screen , how do I redirect it to log
file using logging error
     because the moment assert ret=3D=3D0 becomes true the program exits

def run_cmd_and_verify(cmd, timeout=3D1000):
    try:
        out, err, ret =3D run(cmd, timeout=3Dtimeout)
        assert ret =3D=3D0,"ERROR (ret %d): " \

                " \nout: %s\nerr: %s\n" % (ret, out, err)
    except Exception as e:
        logging.error("Failed to run %s got %s" % (cmd, e))
        return False
    return True

#script_10.py
Failed to run  mount /nfs got ERROR (ret 1):
out:
host-44-3 exited with status 1
err:
host-44-3: mount_efs:  on /nfs: efs is already mounted

3. my function def has 1000 but Iam using 3600 in the calling fnx etc
, Time out value are overwritten ?
4. Any further improvement particularly on try -except ?


Regards,
Ganesh