Expose os.scandir through Trio's async filesystem API?

Copying over a feature request from user "Manganus" on Discourse:

Since I, personally, hardly know how to write readable code, I regret that I won’t become a contributor to this project.

Anyway, I would love to learn how to wrap os.scandir, until someone (who knows how to write readable code) has incorporated it into trio.

The way trio.Path.iterdir works would IMHO fit perfectly (given that I understand it right.) It seems to be an async constructor that calls os.listdir in a worker thread and then returns a regular generator (that does the actual yielding of results).

The main point is the DirEntry objects. 😉

I guess the main problem is the caching of DirEntry.stat(). If the data is in cache, you don’t really wish to await the result. But if not, you wouldn’t wish to block the execution.

Start by reading Trio's existing trio.Path.iterdir implementation and the async filesystem API. Compare the desired os.scandir behavior with DirEntry.stat() caching and determine how cached and uncached results should interact with async execution. Done means the API design and its behavior are agreed, implemented, and covered by tests.