On 12/5/2012 7:48 PM, rh wrote:
On Wed, 5 Dec 2012 18:42:37 +0100
Bruno Dupuis <python.ml.bruno.dup...@lisael.org> wrote:
On Wed, Dec 05, 2012 at 08:48:30AM -0800, rh wrote:
I have argparse working with one exception. I wanted the program to
print out usage when no command line options are given. But I only
came across other examples where people didn't use argparse but
instead printed out a separate usage statement. So they used
argparse for everything but the case where no command line args are
given.
this is quite raw, but i'd add
import sys
if len(sys.argv) == 1:
sys.argv.append('-h')
This works too. I guess I like the print_usage() method better.
Being new to python I have noticed that I had copied a bit of code that did
if len(sys.argv[1:]) == 0:
This needlessly creates and tosses a new object.
You did this:
if len(sys.argv) == 1:
This does not.
The other reply did this:
if len(sys.argv) <= 1:
This allows for the possibility that len(sys.argv) == 0. However, that
can (according to the doc) only happen when starting the interpreter
interactively without a script. Since that does not apply to code within
a .py file, I prefer == 1.
"argv[0] is the script name (it is operating system dependent whether
this is a full pathname or not). If the command was executed using the
-c command line option to the interpreter, argv[0] is set to the string
'-c'. If no script name was passed to the Python interpreter, argv[0] is
the empty string."
--
Terry Jan Reedy
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