Allow keyword argument in `get(asobj=True)`

[huard]

Description

Some converters could accept keyword arguments. For example, some xarray datasets should be opened with decode_timedelta=False, which at the moment is not possible using get.

Environment

• Birdy version used, if any: 0.7.0

[huard]

I suggest we discuss how to do this cleanly.

The first option is simply to call get(asobj=True, **kwds), and then in the code I transfer those kwds to the convert method. My concern with this is that it's obscure; as a user you don't really know what function is going to be used to open the file, and you don't have access to the signature or docstring. If it fails, good luck.

Another option is to deprecate asobj=True, and attach the convert method to the output. So you would do something like:

out = response.get()
out.open(**kwds)

and would be able to inspect help(out.open). I think we could use boltons.funcutils.wraps to do this. A major difference is that out would be an Output instance, not just a string.

We could also leave get as is, and create another method, so we don't break anything.

Thoughts, other ideas ?

[huard]

@cehbrecht Are you using this asobj functionality in rooki ? Would this break anything on your end ?

[huard]

I've got something that would let you do:

>>> wps = WPSClient("http://localhost:5000")
>>> resp = wps.ncml()
>>> [d1, d2, ncml] = resp.load()  # Returns augmented owslib.wps.Output object that have a load method. 
>>> ds = d1.load(decode_times=False)
>>> help(d1.load)
Help on function open_dataset in module xarray.backends.api:

open_dataset(filename_or_obj, group=None, decode_cf=True, mask_and_scale=None, decode_times=True, autoclose=None, concat_characters=True, decode_coords=True, engine=None, chunks=None, lock=None, cache=None, drop_variables=None, backend_kwargs=None, use_cftime=None, decode_timedelta=None)
    Open and decode a dataset from a file or file-like object.
    
    Parameters
    ----------
    filename_or_obj : str, Path, file-like or DataStore
        Strings and Path objects are interpreted as a pat

One issue is that there is no nesting. If you load a metalink or zip, we cannot attach a load method to their content, at least not without doing some horrible coding.

[cehbrecht]

@cehbrecht Are you using this asobj functionality in rooki ? Would this break anything on your end ?

rooki is just using the get to retrieve the metalink download URL:
https://github.com/roocs/rooki/blob/b093bc544280d87ebaf74ddcf8cac6535e33a514/rooki/results.py#L33

[cehbrecht]

Another option is to deprecate asobj=True, and attach the convert method to the output. So you would do something like:

out = response.get()
out.open(**kwds)

I would also be in favor of using adapted methods for outputs.

To be on the save side we could deprecate the existing get function to avoid breaking our existing notebooks.

[cehbrecht]

One issue is that there is no nesting. If you load a metalink or zip, we cannot attach a load method to their content, at least not without doing some horrible coding.

the load method for a metalink output could maybe implement some of the things we currently have in rooki:
https://github.com/roocs/rooki/blob/master/rooki/results.py

[cehbrecht]

@huard If you choose a new method we need to decide for a new method name, excluding get: load, open, retrieve, result, output, ..., ?

The load method could return a new Result object which can then have access interpretations for the different output types (literal, mime-types).