feat(bzlmod)!: Calling pip multiple times allowing for multiple Python versions (#1254)

Implementing the capability to call pip bzlmod extension multiple times.
We can now call the pip extension with the same hub name multiple times.
This allows a user to have multiple different requirement files based on
the Python version.

With workspace, we need incompatible aliases because you get
@pip//tabulate or @pip_tabulate//:pkg.
The requirement() macro hides this, but changing the flag becomes a
breaking change if you've manually referenced things. With bzlmod,
though, the @pip_tabulate style isn't a realistic option (you'd have to
use_repo everything, which is a huge pain).

So we have chosen to have `@pip//tabulate`.

This commit implements that capability for pip.parse to determine the
Python version from programmatically
the provided interpreter.

See 


https://github.com/bazelbuild/rules_python/blob/76aab0f91bd614ee1b2ade310baf28c38695c522/python/extensions/pip.bzl#L88

For more in-depth implementation details.

INTERFACE CHANGE::

- pip.parse argument python_version is introduced but not required. When
possible, it is
  inferred.

BREAKING CHANGE:
* `pip.parse()` extension: the `name` attribute is renamed `hub_name`.
This is to reflect
that the user-provided name isn't unique to each `pip.parse()` call. We
now have a hub that is created, and each
   pip.parse call creates a spoke.
* `pip.parse()` extension: the `incompatible_generate_aliases` arg is
removed; behavior
     has changed to assume it is always True.
* `pip.parse()` calls are collected under the same `hub_name` to support
multiple Python versions under the same resulting repo name (the hub
name0.


Close: #1229

1 files changed, 2 insertions, 3 deletions

diff --git a/README.md b/README.md
index cf4b04e..69be729 100644
--- a/README.md
+++ b/README.md
@@ -96,8 +96,7 @@ use_repo(interpreter, "interpreter")
 
 pip = use_extension("@rules_python//python/extensions:pip.bzl", "pip")
 pip.parse(
-    name = "pip",
-    incompatible_generate_aliases = True,
+    hub_name = "pip",
     python_interpreter_target = "@interpreter//:python",
     requirements_lock = "//:requirements_lock.txt",
     requirements_windows = "//:requirements_windows.txt",
@@ -201,7 +200,7 @@ central external repo and individual wheel external repos.
 
 ```python
 pip.parse(
-    name = "my_deps",
+    hub_name = "my_deps",
     requirements_lock = "//:requirements_lock.txt",
 )