Datafile cloud/local path duality

[cortadocodes]

Datafile increasingly represents a hybrid local/cloud object with recent additions of the local_path and cloud_path attributes while the original path attribute remains. We've been thinking about if the natural and intuitive thing to do is just be explicit about cloud and local paths and deprecate path.

The problem we have currently is that path is a required path at instantiation which we need to make Datafile a Pathable, but this means we prioritise one either the cloud path or the local path. We can't have two equal-priority pathables without Pathable being used by composition for cloud_path and local_path in the constructor rather than as a mixin. At the moment, to instantiate a Datafile, you have to specify one of:

• path and cloud_path where path is a local path
• path and local_path where path is a cloud path

There is disparity in these options (which path is used for path matters to some extent) and problems will likely ensue if all of path, cloud_path, and local_path are specified.

Ultimately, we may need to deprecate path and fully embrace the duality of cloud/local. This will have implications for Pathable so we'll have to observe user behaviour as to whether the its capabilities are actually fully used or not.

[cortadocodes]

This issue arose from #236

[cortadocodes]

Linked to #414

[cortadocodes]

Partially resolved by #432