Add arrow3 package with just empty __init__.py

[ghuls]

Currently when installing the 3 arrow3 packages, the structure looks like this:

$ ls /lib/python3.11/site-packages/arro3/
compute core  io     

When importing the modules in ipython, tab completion is not working (to find the functions in each module

In [4]: import arro3.io

In [5]: import arro3.core

In [6]: import arro3.compute

In [7]: arro3.io.<TAB> ==> no list of functions.

When importing them with an alias, tab completion works:

In [1]: import arro3.io as arro3_io

In [2]: import arro3.compute as arro3_compute

In [3]: import arro3.core as arro3_core

In [4]: arro3_io.<TAB>
 infer_csv_schema()   read_csv()           read_ipc_stream()    read_parquet()       store                write_ipc()          write_json()         write_parquet()     
 infer_json_schema()  read_ipc()           read_json()          read_parquet_async() write_csv()          write_ipc_stream()   write_ndjson()                           

When adding just an empty _init__.py at /lib/python3.11/site-packages/arro3/__init__.py, tab completion works:

In [1]: import arro3.io as arro3_io

In [2]: import arro3.compute as arro3_compute

In [3]: import arro3.core as arro3_core

In [4]: arro3.io.<TAB>
 infer_csv_schema()   read_csv()           read_ipc_stream()    read_parquet()       store                write_ipc()          write_json()         write_parquet()     
 infer_json_schema()  read_ipc()           read_json()          read_parquet_async() write_csv()          write_ipc_stream()   write_ndjson()           

# Create empty file.
$ touch /lib/python3.11/site-packages/arro3/__init__.py

It would be great if this file would exist by default, as without tab completion, it is very hard to discover the functions without looking at the documentation.

[kylebarron]

When adding just an empty _init__.py at /lib/python3.11/site-packages/arro3/__init__.py, tab completion works:

In theory, that is supposed to break namespace packaging: https://packaging.python.org/en/latest/guides/packaging-namespace-packages/#native-namespace-packages

All that is required to create a native namespace package is that you just omit __init__.py from the namespace package directory

[kylebarron]

It seems that this is a bug with how IPython handles namespace packages? If there's no __init__.py it should still look inside each directory, to see if the inner directory contains an __init__.py file.