On 12/11/24 10:17, Cameron Simpson via Python-list wrote:
On 11Nov2024 18:24, dieter.mau...@online.de <dieter.mau...@online.de>
wrote:
Loris Bennett wrote at 2024-11-11 15:05 +0100:
I have the following in my program:
try:
logging.config.fileConfig(args.config_file)
config = configparser.ConfigParser()
config.read(args.config_file)
if args.verbose:
print(f"Configuration file: {args.config_file}")
except FileNotFoundError:
print(f"Error: configuration file {args.config_file} not
found. Exiting.")
My questions are:
1. Should I be surprised by this behaviour?
No. Python has behaved as-programmed.
2. In terms of generating a helpful error message, how should one
distinguish between the config file not existing and the log file not
existing?
Generally you should put a try/except around the smallest possible piece
of code. So:
config = configparser.ConfigParser()
try:
config.read(args.config_file)
except FileNotFoundError as e:
print(f"Error: configuration file {args.config_file} not found:
{e}")
This way you know that the config file was missing.
Augmenting @Cameron's excellent advice: please research "Separation of
Concerns", eg https://en.wikipedia.org/wiki/Separation_of_concerns
(which overlaps with one interpretation of SOLID's "Single
Responsibility Principle" and the *nix philosophy of "do one thing, and
do it well").
If you were to explain the code-snippet in English (or ...) it has
several parts/concerns:
- configure the log
- instantiate ConfigParser()
- read the env.file
- advise verbosity-setting
- handle file-error
- (and, but not appearing) terminate execution
A block of code (see indentation for rough definition of "block") should
achieve one thing ("concern"). Thus, the advice to separate-out the
file-read and attendant defensive-coding.
This anticipates the problem (2) of distinguishing the subject of any
one error/stack-trace from any others - and, arguably, makes the code
easier to read.
--
Regards,
=dn
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