chore: Add a platform_interface type to export from each platform

This avoids the repetition of the platform checks in __main__.py
by defining a dataclass with `get_python_configurations` and `build`.

cibuildwheel/__main__.py

@@ -7,7 +7,7 @@ import sys
 import tarfile
 import textwrap
 import typing
-from collections.abc import Sequence, Set
+from collections.abc import Set
 from pathlib import Path
 from tempfile import mkdtemp
 
@@ -19,9 +19,9 @@ import cibuildwheel.windows
 from cibuildwheel.architecture import Architecture, allowed_architectures_check
 from cibuildwheel.logger import log
 from cibuildwheel.options import CommandLineArguments, Options, compute_options
+from cibuildwheel.platform_interface import PlatformInterface
 from cibuildwheel.typing import (
     PLATFORMS,
-    GenericPythonConfiguration,
     PlatformName,
     assert_never,
 )
@@ -244,6 +244,16 @@ def _compute_platform(args: CommandLineArguments) -> PlatformName:
     return _compute_platform_ci()
 
 
+def get_platform_interface(platform: PlatformName) -> PlatformInterface:
+    if platform == "linux":  # noqa: SIM116
+        return cibuildwheel.linux.interface
+    elif platform == "windows":
+        return cibuildwheel.windows.interface
+    elif platform == "macos":
+        return cibuildwheel.macos.interface
+    assert_never(platform)
+
+
 def build_in_directory(args: CommandLineArguments) -> None:
     platform: PlatformName = _compute_platform(args)
     options = compute_options(platform=platform, command_line_arguments=args, env=os.environ)
@@ -257,8 +267,9 @@ def build_in_directory(args: CommandLineArguments) -> None:
         print(msg, file=sys.stderr)
         sys.exit(2)
 
+    interface = get_platform_interface(platform)
     identifiers = get_build_identifiers(
-        platform=platform,
+        interface=interface,
         build_selector=options.globals.build_selector,
         architectures=options.globals.architectures,
     )
@@ -304,14 +315,7 @@ def build_in_directory(args: CommandLineArguments) -> None:
         with cibuildwheel.util.print_new_wheels(
             "\n{n} wheels produced in {m:.0f} minutes:", output_dir
         ):
-            if platform == "linux":
-                cibuildwheel.linux.build(options, tmp_path)
-            elif platform == "windows":
-                cibuildwheel.windows.build(options, tmp_path)
-            elif platform == "macos":
-                cibuildwheel.macos.build(options, tmp_path)
-            else:
-                assert_never(platform)
+            interface.build(options, tmp_path)
     finally:
         # avoid https://github.com/python/cpython/issues/86962 by performing
         # cleanup manually
@@ -354,25 +358,9 @@ def print_preamble(platform: str, options: Options, identifiers: list[str]) -> N
 
 
 def get_build_identifiers(
-    platform: PlatformName, build_selector: BuildSelector, architectures: Set[Architecture]
+    interface: PlatformInterface, build_selector: BuildSelector, architectures: Set[Architecture]
 ) -> list[str]:
-    python_configurations: Sequence[GenericPythonConfiguration]
-
-    if platform == "linux":
-        python_configurations = cibuildwheel.linux.get_python_configurations(
-            build_selector, architectures
-        )
-    elif platform == "windows":
-        python_configurations = cibuildwheel.windows.get_python_configurations(
-            build_selector, architectures
-        )
-    elif platform == "macos":
-        python_configurations = cibuildwheel.macos.get_python_configurations(
-            build_selector, architectures
-        )
-    else:
-        assert_never(platform)
-
+    python_configurations = interface.get_python_configurations(build_selector, architectures)
     return [config.identifier for config in python_configurations]
 
 

cibuildwheel/linux.py

@@ -12,6 +12,7 @@ from .architecture import Architecture
 from .logger import log
 from .oci_container import OCIContainer
 from .options import Options
+from .platform_interface import PlatformInterface
 from .typing import OrderedDict, PathOrStr, assert_never
 from .util import (
     AlreadyBuiltWheelError,
@@ -483,3 +484,6 @@ def troubleshoot(options: Options, error: Exception) -> None:
             print("  Files detected:")
             print("\n".join(f"    {f}" for f in so_files))
             print()
+
+
+interface = PlatformInterface(get_python_configurations=get_python_configurations, build=build)

cibuildwheel/macos.py

@@ -19,6 +19,7 @@ from .architecture import Architecture
 from .environment import ParsedEnvironment
 from .logger import log
 from .options import Options
+from .platform_interface import PlatformInterface
 from .typing import Literal, PathOrStr, assert_never
 from .util import (
     CIBW_CACHE_PATH,
@@ -622,3 +623,6 @@ def build(options: Options, tmp_path: Path) -> None:
             f"Command {error.cmd} failed with code {error.returncode}. {error.stdout}"
         )
         sys.exit(1)
+
+
+interface = PlatformInterface(get_python_configurations=get_python_configurations, build=build)

cibuildwheel/platform_interface.py

@@ -0,0 +1,19 @@
+from __future__ import annotations
+
+import dataclasses
+from collections.abc import Callable, Sequence, Set
+from pathlib import Path
+
+from .architecture import Architecture
+from .options import Options
+from .typing import GenericPythonConfiguration
+from .util import BuildSelector
+
+
+# Can't make it frozen because we monkeypatch "build" in unit tests
+@dataclasses.dataclass()
+class PlatformInterface:
+    get_python_configurations: Callable[
+        [BuildSelector, Set[Architecture]], Sequence[GenericPythonConfiguration]
+    ]
+    build: Callable[[Options, Path], None]

cibuildwheel/windows.py

@@ -20,6 +20,7 @@ from .architecture import Architecture
 from .environment import ParsedEnvironment
 from .logger import log
 from .options import Options
+from .platform_interface import PlatformInterface
 from .typing import PathOrStr, assert_never
 from .util import (
     CIBW_CACHE_PATH,
@@ -574,3 +575,6 @@ def build(options: Options, tmp_path: Path) -> None:
             f"Command {error.cmd} failed with code {error.returncode}. {error.stdout}"
         )
         sys.exit(1)
+
+
+interface = PlatformInterface(get_python_configurations=get_python_configurations, build=build)

unit_test/main_tests/conftest.py

@@ -85,9 +85,9 @@ def platform(request, monkeypatch):
 def intercepted_build_args(monkeypatch):
     intercepted = ArgsInterceptor()
 
-    monkeypatch.setattr(linux, "build", intercepted)
-    monkeypatch.setattr(macos, "build", intercepted)
-    monkeypatch.setattr(windows, "build", intercepted)
+    monkeypatch.setattr(linux.interface, "build", intercepted)
+    monkeypatch.setattr(macos.interface, "build", intercepted)
+    monkeypatch.setattr(windows.interface, "build", intercepted)
 
     yield intercepted
 

unit_test/options_test.py

@@ -7,7 +7,7 @@ from pathlib import Path
 
 import pytest
 
-from cibuildwheel.__main__ import get_build_identifiers
+from cibuildwheel.__main__ import get_build_identifiers, get_platform_interface
 from cibuildwheel.bashlex_eval import local_environment_executor
 from cibuildwheel.environment import parse_environment
 from cibuildwheel.options import (
@@ -49,8 +49,9 @@ def test_options_1(tmp_path, monkeypatch):
 
     options = Options(platform="linux", command_line_arguments=args, env={})
 
+    interface = get_platform_interface("linux")
     identifiers = get_build_identifiers(
-        platform="linux",
+        interface=interface,
         build_selector=options.globals.build_selector,
         architectures=options.globals.architectures,
     )