refactor: split toolchains and repositories (#323)

### Type of change

Currently, rules_py_dependencies and rules_py_toolchains are exported
from the same bzl file which makes it impossible to depend on another
rule and load from at the same since both macros are in the same file.
This changes this to allow adding a dependency and loading from it.

- Refactor (a code change that neither fixes a bug or adds a new
feature)

**For changes visible to end-users**

- Breaking change (this change will force users to change their own code
or config)
- Relevant documentation has been updated

### Test plan

- Covered by existing test cases

WORKSPACE

@@ -15,6 +15,10 @@ load("//py:repositories.bzl", "rules_py_dependencies")
 # Fetch dependencies which users need as well
 rules_py_dependencies()
 
+load("//py:toolchains.bzl", "rules_py_toolchains")
+
+rules_py_toolchains()
+
 # Load the Python toolchain for rules_docker
 register_toolchains("//:container_py_toolchain")
 

e2e/smoke/WORKSPACE.bazel

@@ -56,6 +56,10 @@ load("@aspect_rules_py//py:repositories.bzl", "rules_py_dependencies")
 
 rules_py_dependencies()
 
+load("@aspect_rules_py//py:toolchains.bzl", "rules_py_toolchains")
+
+rules_py_toolchains()
+
 # "Installation" for rules_python
 load("@rules_python//python:repositories.bzl", "py_repositories", "python_register_toolchains")
 

e2e/use_release/WORKSPACE.bazel

@@ -9,9 +9,11 @@ local_repository(
 # you should fetch it *before* calling this.
 # Alternatively, you can skip calling this function, so long as you've
 # already fetched all the dependencies.
-load("@aspect_rules_py//py:repositories.bzl", "rules_py_dependencies", "rules_py_toolchains")
+load("@aspect_rules_py//py:repositories.bzl", "rules_py_dependencies")
 
-rules_py_dependencies(register_toolchains = False)
+rules_py_dependencies()
+
+load("@aspect_rules_py//py:toolchains.bzl", "rules_py_toolchains")
 
 # Force use of pre-built release binaries regardless of the content of /tools/version.bzl
 rules_py_toolchains(is_prerelease = False)

py/extensions.bzl

@@ -1,6 +1,6 @@
 "Module Extensions used from MODULE.bazel"
 
-load(":repositories.bzl", "DEFAULT_TOOLS_REPOSITORY", "rules_py_toolchains")
+load(":toolchains.bzl", "DEFAULT_TOOLS_REPOSITORY", "rules_py_toolchains")
 load("//tools:version.bzl", "IS_PRERELEASE")
 
 py_toolchain = tag_class(attrs = {

py/repositories.bzl

@@ -6,17 +6,10 @@ See https://docs.bazel.build/versions/main/skylark/deploying.html#dependencies
 
 load("@bazel_tools//tools/build_defs/repo:http.bzl", _http_archive = "http_archive")
 load("@bazel_tools//tools/build_defs/repo:utils.bzl", "maybe")
-load("//py/private/toolchain:autodetecting.bzl", _register_autodetecting_python_toolchain = "register_autodetecting_python_toolchain")
-load("//py/private/toolchain:tools.bzl", "TOOLCHAIN_PLATFORMS", "prebuilt_tool_repo")
-load("//py/private/toolchain:repo.bzl", "prerelease_toolchains_repo", "toolchains_repo")
-load("//tools:version.bzl", "IS_PRERELEASE")
 
 def http_archive(name, **kwargs):
     maybe(_http_archive, name = name, **kwargs)
 
-register_autodetecting_python_toolchain = _register_autodetecting_python_toolchain
-
-DEFAULT_TOOLS_REPOSITORY = "rules_py_tools"
 
 # WARNING: any changes in this function may be BREAKING CHANGES for users
 # because we'll fetch a dependency which may be different from one that
@@ -26,12 +19,8 @@ DEFAULT_TOOLS_REPOSITORY = "rules_py_tools"
 # and released only in semver majors.
 
 # buildifier: disable=unnamed-macro
-def rules_py_dependencies(register_toolchains = True):
-    """Fetch rules_py's dependencies
-
-    Args:
-        register_toolchains: whether to also do default toolchain registration
-    """
+def rules_py_dependencies():
+    """Fetch rules_py's dependencies"""
 
     # The minimal version of bazel_skylib we require
     http_archive(
@@ -53,30 +42,4 @@ def rules_py_dependencies(register_toolchains = True):
         sha256 = "c68bdc4fbec25de5b5493b8819cfc877c4ea299c0dcb15c244c5a00208cde311",
         strip_prefix = "rules_python-0.31.0",
         url = "https://github.com/bazelbuild/rules_python/releases/download/0.31.0/rules_python-0.31.0.tar.gz",
-    )
-
-    if register_toolchains:
-        rules_py_toolchains()
-
-def rules_py_toolchains(name = DEFAULT_TOOLS_REPOSITORY, register = True, is_prerelease = IS_PRERELEASE):
-    """Create a downloaded toolchain for every tool under every supported platform.
-
-    Args:
-        name: prefix used in created repositories
-        register: whether to call the register_toolchains, should be True for WORKSPACE and False for bzlmod.
-        is_prerelease: True iff there are no pre-built tool binaries for this version of rules_py
-    """
-    if is_prerelease:
-        prerelease_toolchains_repo(name = name)
-        if register:
-            native.register_toolchains(
-                "@aspect_rules_py//py/private/toolchain/venv/...",
-                "@aspect_rules_py//py/private/toolchain/unpack/...",
-            )
-    else:
-        for platform in TOOLCHAIN_PLATFORMS.keys():
-            prebuilt_tool_repo(name = ".".join([name, platform]), platform = platform)
-        toolchains_repo(name = name, user_repository_name = name)
-
-        if register:
-            native.register_toolchains("@{}//:all".format(name))
+    )

py/toolchains.bzl

@@ -0,0 +1,34 @@
+"""Declare toolchains"""
+
+load("//py/private/toolchain:autodetecting.bzl", _register_autodetecting_python_toolchain = "register_autodetecting_python_toolchain")
+load("//py/private/toolchain:repo.bzl", "prerelease_toolchains_repo", "toolchains_repo")
+load("//py/private/toolchain:tools.bzl", "TOOLCHAIN_PLATFORMS", "prebuilt_tool_repo")
+load("//tools:version.bzl", "IS_PRERELEASE")
+
+
+register_autodetecting_python_toolchain = _register_autodetecting_python_toolchain
+
+DEFAULT_TOOLS_REPOSITORY = "rules_py_tools"
+
+def rules_py_toolchains(name = DEFAULT_TOOLS_REPOSITORY, register = True, is_prerelease = IS_PRERELEASE):
+    """Create a downloaded toolchain for every tool under every supported platform.
+
+    Args:
+        name: prefix used in created repositories
+        register: whether to call the register_toolchains, should be True for WORKSPACE and False for bzlmod.
+        is_prerelease: True iff there are no pre-built tool binaries for this version of rules_py
+    """
+    if is_prerelease:
+        prerelease_toolchains_repo(name = name)
+        if register:
+            native.register_toolchains(
+                "@aspect_rules_py//py/private/toolchain/venv/...",
+                "@aspect_rules_py//py/private/toolchain/unpack/...",
+            )
+    else:
+        for platform in TOOLCHAIN_PLATFORMS.keys():
+            prebuilt_tool_repo(name = ".".join([name, platform]), platform = platform)
+        toolchains_repo(name = name, user_repository_name = name)
+
+        if register:
+            native.register_toolchains("@{}//:all".format(name))