get_wf should help users if they don't know what presets are available

[mkhorton]

In particular, here:

atomate/atomate/vasp/workflows/base/core.py

Line 39 in f23bedb

d = loadfn(os.path.join(module_dir, "library", wf_filename))

Something like:

if os.path.isfile(os.path.join(module_dir, "library", wf_filename)):
    d = loadfn(os.path.join(module_dir, "library", wf_filename))
else:
    library_options = glob(os.path.join(module_dir, "library", "*.yaml"))
    raise ValueError(f"Preset does not exist in library, please choose from: {library_options}")

[mkhorton]

This really needs more work besides anyway as part of a broader clean up, including what common params are, how one are meant to use them, etc. (I know the answer to this, but I suspect the current docstring common_params: (dict) set common params might be insufficient for new users).

[shyuep]

I would suggest a simple factory:

class WFFactory:
    names = set(glob.glob(module_dir / "*.yaml"))
    @classmethod
    def get_wf(cls, name):
       if name not in cls.names:
            raise some error.
        ....