Print usage when no args provided

[kinow]

Hi,

Running maestro for the first time ever today from the develop branch. I first tried maestro without anything else, but it resulted in a traceback.

(venv) kinow@ranma:~/Development/python/workspace/maestrowf$ maestro 
Traceback (most recent call last):
  File "/home/kinow/Development/python/workspace/maestrowf/venv/bin/maestro", line 8, in <module>
    sys.exit(main())
  File "/home/kinow/Development/python/workspace/maestrowf/maestrowf/maestro.py", line 495, in main
    if not hastattr(args, 'func'):
NameError: name 'hastattr' is not defined

I think it would be best to print the program usage instead? So if users are not aware, or not sure, which subcommand/subparser to trigger, they can read the usage and decide then.

Thanks for maestro! 👋
-Bruno

EDIT: closes #188 (hadn't seen the issue, sorry)

[FrankD412]

Hi @kinow -- Thanks for the contribution! Must say you have impeccable timing; I had someone encounter this recently, so it was on my mind.

I've approved the MR to run through our CI and will review the code in a bit. :)

Thanks again for your contribution!

[FrankD412]

@kinow -- it looks like you can set the default function. I generally avoid hasattr since that's been considered bad practice from what I've seen. Talking with @jwhite242 and with some searching, it seems that this might be the better bet:

    parser = ArgumentParser(
        prog="maestro",
        description="The Maestro Workflow Conductor for specifying, launching"
        ", and managing general workflows.",
        formatter_class=RawTextHelpFormatter)
    # This call applies a default function to the main parser as described
    # here: https://stackoverflow.com/a/61680800
    parser.set_defaults(func=lambda args: parser.print_help())

[kinow]

Hi @FrankD412

I normally use hasattr or wrap it in a try-except block for a AttributeError (latter is normally faster IIRC?). But I have no preference, it was just the first idea that came to my mind.

+1 to using a default value if that's available. Give me 10 mins and I'll update the branch and test locally…