How to implement CLI option as "repeat to increase value"?

Platform Core
1

Imagine that I have an app, my_app, I want to design its CLI option as:

my_app -v

with -v being “verbose”, and to increase verbosity, user just repeat that option, like:

my_app -vv

How to archive that with Gio.Application.add_main_option and friends?

2

GOptionContext can’t do that, so you just have to do the parsing yourself.

1 Like
3

I don’t know pygi well enough off the top of my head, so here’s a C version which hopefully you can translate to Python :slight_smile: You can use a combination of G_OPTION_FLAG_NO_ARG and G_OPTION_ARG_CALLBACK. For example:

/* gcc -Wall -g -O0 -o foo foo.c `pkg-config --cflags --libs glib-2.0` */
#include <stdio.h>
#include <glib.h>

static guint verbosity = 0;

static gboolean verbosity_callback (const gchar    *option_name,
				    const gchar    *value,
				    gpointer        data,
				    GError        **error)
{
    verbosity++;
    return TRUE;
}

static GOptionEntry entries[] = {
    { "verbose", 'v', G_OPTION_FLAG_NO_ARG, G_OPTION_ARG_CALLBACK, verbosity_callback, "Increase verbosity", "" },
    { NULL }
};

int
main (int argc, char **argv)
{
    GOptionContext *context;
    GError *error = NULL;

    context = g_option_context_new ("- test verbosity flag");
    g_option_context_add_main_entries (context, entries, NULL);

    if (!g_option_context_parse (context, &argc, &argv, &error)) {
        printf ("invalid options: %s\n", error->message);
        exit (1);
    }

    printf ("verbosity level %u\n", verbosity);
    return 0;
}

If you run it like “foo -vvv” it will print “verbosity level 3”.

1 Like
4

Thanks. I hope that GTK developers will add this feature, because this pattern seems to be popular enough.

5

It’s extremely unlikely that will happen. You can easily use the callback notation to do that yourself, and that kind of incremental globbing is only ever useful for a very small subset of command line arguments.

6

Among Python applications, this pattern is popular enough that it is added to Python standard library:

>>> parser = argparse.ArgumentParser()
>>> parser.add_argument('--verbose', '-v', action='count', default=0)
>>> parser.parse_args(['-vvv'])
Namespace(verbose=3)

and also welknown 3-rd party library:

@click.command()
@click.option('-v', '--verbose', count=True)
def log(verbose):
    click.echo('Verbosity: %s' % verbose)
7

It doesn’t really matter what’s popular with Python, though.

1 Like
8

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