Hi. Here is my sub-project structure. I have added

src/py/sub-project

to the roots.

src/py/sub-project
    sub_project/
        __init__.py
        __main__.py
        ...
    tests/
        test_sub_project.py

When I run

./pants tailor

, I see two

BUILD

files added, one in

src/py/sub-project/sub_project

, the other in

src/py/sub-project/tests

. Why isn’t there a

BUILD

file in

src/py/sub-project

if that is the root? Now, in

src/py/sub-project/sub_project/BUILD

it has generated a

pex_binary

entry with name

__main__

and

entry_point="__main__.py"

. When I as a developer add a

__main__.py

file under a Python package (

sub_project

in this case), its goal is to provide a standard entrypoint for the package, not entrypoint in itself as if

__main__.py

was in

PYTHONPATH

(which is what name

__main__

for

pex_binary

looks to me). If I want to make

sub_project

package into something that other subprojects can depend on, where do I declare that it “publishes” the sources under name

sub_project

? Intuitively, I would put it under

src/py/sub-project/BUILD

because that directory (

src/py/sub-project

) sees the Python package

sub_project

in its entirety. But this seems to not match what

./pants tailor

generates. If I put it under

src/py/sub-project/sub_project/BUILD

in

python_sources

, will the contents be under

sub_project

Python package namespace?

Hi Jāzeps 👋

Why isn’t there a

BUILD

file in

src/py/sub-project

if that is the root?

Pants tailor will only create

BUILD

files where there are “targets” that needs to be declared. If you don’t have any files there, then there are no targets to declare there (you may want to create a BUILD file there for a

python_distribution

perhaps, but that will be a manual operation)

Thanks @curved-television-6568 The note about BUILD file placement not having any effect on Python packages is very useful. I am still not convinced how the package name will be worked out though. Maybe I will reformulate my vague question after a few experiments.

I think I see the source of the confusion: BUILD files just say "here is some code", and maybe provide metadata to describe that code. You can have many BUILD files inside a single package tree (one per directory is a common way to do it).