Manolo Martínez wrote:
> On 12/01/15 at 12:00pm, Steven D'Aprano wrote:
> > I'm trying to understand why vars() exists. Does anyone use it?
>
> Well, I have this little podcast aggregator
> (https://github.com/manolomartinez/greg) that I and a bunch of other
> people use. I started writing it some years ago, and the code is a bit
> of a palimpsest, newer functionality reflecting my (somewhat) better
> understanding of the language. One of the oldest bits is this main()
> function:
>
> def main(): # parse the args and call whatever function was
selected
> try:
> args = parser.parse_args(sys.argv[1:])
> args.func(vars(args))
> except AttributeError as err:
> if str(err) == "\'Namespace\' object has no
attribute \'func\'":
> parser.print_help()
> else:
> print("Something has gone wrong:
{}".format(err), file = sys.stderr, flush = True)
>
>
> To judge by this thread, this is probably wrong/noobish?
What probably is typical for a beginner in that snippet is that you don't
trust the exception system and handle exceptions that will never occur once
the script is debugged. Just write
args = parser.parse_args()
args.func(vars(args))
Now vars(). I see nothing wrong with it, but when I look into one of your
func implementations
> def info(args): # Provides information of a number of feeds
> session = Session(args)
> if "all" in args["names"]:
> feeds = session.list_feeds()
> else:
> feeds = args["names"]
> for feed in feeds:
> pretty_print(session, feed)
I come to the conclusion that passing args directly could make your life
easier:
def info(args):
"""Provides information of a number of feeds"""
session = Session(args)
if "all" in args.names:
feeds = session.list_feeds()
else:
feeds = args.names
for feed in feeds:
pretty_print(session, feed)
As far as I can see there is only one place where the key is not a constant,
and you can rewrite that from
> try:
> if args[value]:
> return args[value]
> except KeyError:
> pass
to
try:
answer = getattr(args, value)
if answer:
return answer
except AttributeError:
pass
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