Re: Is it ‘allowed’ to get parameters like this

[Lawrence D’Oliveiro]

On Friday, August 12, 2016 at 1:28:04 AM UTC+12, Cecil Westerhof wrote:

> As I understood it getopt is the way to get the parameters for your
> script. But at the moment it looks a bit like overkill, my script does
> not have much parameters as parameter_error shows:

That’s fine. But your command-line needs are so simple, I wouldn’t bother with the “--” business either. Just take the interval as a single argument. Here’s how I would do it:

    if len(sys.argv) == 2 :
        periodspec = sys.argv[1]
    elif len(sys.argv) == 1 :
        periodspec = "all"
    else :
        raise RuntimeError("usage:\n    {} [period]" % sys.argv[0])
    #end if

    today = time.strftime("%Y-%m-%d") # or whatever
      # original did “select current_date” from SQLite
    if re.fullmatch(r"^\d+$", periodspec) != None :
        period = int(periodspec)
    else :
        period = \
            {
                "today" : lambda : today + "%",
                "this-month" : lambda : today[0:8] + "%",
                "this-year" : lambda : today[0:5] + "%",
                "all" : lambda : "%",
            }.get(periodspec, lambda : None)()
        if period == None :
            raise RuntimeError("{}: unrecognized period spec “%s”" % periodspec)
        #end if
    #end if
    sys.stderr.write("period = %s\n" % repr(period)) # debug
    # ...
    # vmstat_params = (period, slice_length)
    # ... etc

So you would call that like

    ./demo 5
    ./demo today
    ./demo

etc. And as a bonus, it will accept any integer interval, not just your original limited set. And you see how I wrote the table of symbolic intervals? That makes it easy to add new entries.