Question

I’m trying to use argparse to deal with command line arguments to my application, bur I’ve been having some trouble with gstreamer (which my application uses). When I give the -h option for my application, instead of it showing the help message I defined for the arguments of my program, it show a weird gstreamer help message, omitting the help for my arguments.

I have the following parser definition in my code:

parser = argparse.ArgumentParser()
parser.add_argument("-c", "--capture", help="Specifies the capture device.\n 0 - Webcam \n 1 - Kinect", type=int, choices=[0, 1], default=0)
parser.add_argument("-i", "--interval", help="Specifies the capture interval in seconds when the auto-capture is on", type=int, choices=[4, 5, 6, 7, 8], default=4)
args = parser.parse_args()

and the message I get when I start my program with -h is (my locale is in Brazilian-Portuguese, but it’s enough to see the general structure of the help message and the lack of help for my optional arguments)

Uso:
  FasTracker.py [OPÇÃO...] - GStreamer initialization

Opções de ajuda:
  -h, --help                        Exibe opções de ajuda
  --help-all                        Exibe todas as opções de ajuda
  --help-gst                        Exibir opções do GStreamer

Am I doing something wrong, or is there a way to supress the Gstreamer help message?

Thanks in advance

Answer 1

I also had the same problem. I am using ubuntu 10.10 + python 2.6 + python-gst0.10 package.

Finally I tracked down the bug to this: import gst before parser.parse_args() modifies sys. To reproduce, put the following code into main.py:

if __name__=='__main__':
    import argparse, sys
    pparser = argparse.ArgumentParser(description='my program')
    pparser.add_argument('--plot', action='store_true', default=False, help="Show a plot")
    pparser.add_argument('--log', action='store_true', default=False, help="Write log output")
    pparser.add_argument('filename', action='store', type=str)
    import gst
    args = pparser.parse_args(sys.argv[1:])

and run python main.py -h. This produces the following buggy output:

Usage:
  main.py [OPTION...] - GStreamer initialization

Help Options:
  -h, --help                        Show help options
  --help-all                        Show all help options
  --help-gst                        Show GStreamer Options

If we remove import gst (or move the statement after parse_args), then the output is correct:

usage: main.py [-h] [--plot] [--log] filename

my program

positional arguments:
  filename

optional arguments:
  -h, --help  show this help message and exit
  --plot      Show a plot
  --log       Write log output