I use GLib to parse some command-line options. The problem is that I want to make two of those options mandatory so that the program terminates with the help screen if the user omits them.

My code looks like this:

static gint line   = -1;
static gint column = -1;

static GOptionEntry options[] =
{
    {"line", 'l', 0, G_OPTION_ARG_INT, &line, "The line", "L"},
    {"column", 'c', 0, G_OPTION_ARG_INT, &column, "The column", "C"},
    {NULL}
};

...

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

    context = g_option_context_new ("- test");
    g_option_context_add_main_entries (context, options, NULL);

    if (!g_option_context_parse(context, &argc, &argv, &error))
    {
        usage(error->message, context);
    }

    ...

    return 0;
}

If I omit one of those parameters or both on the command-line g_option_context_parse() still succeeds and the values in question (line and or column) are still -1. How can I tell GLib to fail parsing if the user doesn't pass both options on the command-line? Maybe I'm just blind but I couldn't find a flag I can put into my GOptionEntry data structure to tell it to make those fields mandatory.

Of course I could check if one of those variables is still -1 but then the user could just have passed this value on the command-line and I want to print a separate error message if the values are out of range.