Nwm client transition

[jarq6c]

This PR deprecates hydrotools.caches and hydrotools.nwm_client. Importing these packages results in a FutureWarning that these packages are no longer supported. I would have gone with a DeprecationWarning, but that is not shown to the user by default. Automated tests are removed, as are references in the docs.

[jarq6c]

@aaraney any notes or reservations?

[aaraney]

Im sure we have talked about this idea in the past and my memory is failing me, @jarq6c what are your thoughts on instead of deprecating going with a hard break and replacing the current nwm_client with what is now the nwm_client_new and releasing a new major version of nwm_client?

[jarq6c]

Im sure we have talked about this idea in the past and my memory is failing me, @jarq6c what are your thoughts on instead of deprecating going with a hard break and replacing the current nwm_client with what is now the nwm_client_new and releasing a new major version of nwm_client?

Definitely preferred. Do you have any recommendations for how to do that responsibly?

[jarq6c]

I'm going to rename nwm_client_new on another PR.

[aaraney]

Definitely preferred. Do you have any recommendations for how to do that responsibly?

Ideally we would transition nwm_client_new to nwm_client and deprecate nwm_client_new but forward imports until we decide to officially pull nwm_client_new for good.

I need to explore a bit to see how to do this and cover all cases, but for starters I think the module level __getattr__ semantics added in PEP 562 enable "proxying" one module as if it were another.

[aaraney]

It seems that PEP 562 does provide a means to proxy a package. However, it does seem that there is a fair amount of boilerplate and structural coupling. The below examples are the contents of a namespace package alt.sub that proxies imports to pkg.sub.

# alt/sub/__init__.py

def __getattr__(name: str):
    import importlib
    package_name = "pkg.sub"
    try:
        return importlib.import_module(f".{name!s}", package_name)
    except ImportError:
        mod = importlib.import_module(package_name)
        return getattr(mod, name)

# alt/sub/a.py
# NOTE: This needs to be repeated for **all** python modules in `pkg.sub`.

def __getattr__(name: str):
    import importlib
    package_name = "pkg.sub"
    proxy_name = f"{package_name}.{__name__[len(package_name)+1:]}"
    mod = importlib.import_module(proxy_name)
    return getattr(mod, name)

Take aways:

Im not sure that it is worth creating and maintaining this file structure to deprecate nwm_client_new. IMO I think we should cut a final release of nwm_client_new that warns users to move to nwm_client and provides instructions for installing and how to migrate (if that's even applicable).