typing: allow PathLike objects in addition to strs

Some projects use pathlib or other libraries to encapsulate file system
paths instead of working with strs (or bytes) directly. These classes
implement the os.PathLike interface which the functions in `os.path`
support in addition to strs.

This changes all functions that accept paths to accept PathLike objects
in addition to strings. The way the backend_path attribute is set in
`BuildBackendHookCaller.__init__()` was also modified so the typing was
correct.

Author: gotmax23

src/pyproject_hooks/_impl.py

@@ -6,10 +6,21 @@
 from os.path import abspath
 from os.path import join as pjoin
 from subprocess import STDOUT, check_call, check_output
-from typing import TYPE_CHECKING, Any, Iterator, Mapping, Optional, Sequence
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Iterator,
+    List,
+    Mapping,
+    Optional,
+    Sequence,
+    Union,
+)
 
 from ._in_process import _in_proc_script_path
 
+StrPath = Union[str, "os.PathLike[str]"]
+
 if TYPE_CHECKING:
     from typing import Protocol
 
@@ -18,19 +29,19 @@ class SubprocessRunner(Protocol):
 
         def __call__(
             self,
-            cmd: Sequence[str],
-            cwd: Optional[str] = None,
+            cmd: Sequence[StrPath],
+            cwd: Optional[StrPath] = None,
             extra_environ: Optional[Mapping[str, str]] = None,
         ) -> None:
             ...
 
 
-def write_json(obj: Mapping[str, Any], path: str, **kwargs) -> None:
+def write_json(obj: Mapping[str, Any], path: StrPath, **kwargs) -> None:
     with open(path, "w", encoding="utf-8") as f:
         json.dump(obj, f, **kwargs)
 
 
-def read_json(path: str) -> Mapping[str, Any]:
+def read_json(path: StrPath) -> Mapping[str, Any]:
     with open(path, encoding="utf-8") as f:
         return json.load(f)
 
@@ -43,7 +54,7 @@ def __init__(
         traceback: str,
         message: Optional[str] = None,
         backend_name: Optional[str] = None,
-        backend_path: Optional[Sequence[str]] = None,
+        backend_path: Optional[Sequence[StrPath]] = None,
     ) -> None:
         # Preserving arg order for the sake of API backward compatibility.
         self.backend_name = backend_name
@@ -68,8 +79,8 @@ def __init__(self, traceback: str) -> None:
 
 
 def default_subprocess_runner(
-    cmd: Sequence[str],
-    cwd: Optional[str] = None,
+    cmd: Sequence[StrPath],
+    cwd: Optional[StrPath] = None,
     extra_environ: Optional[Mapping[str, str]] = None,
 ) -> None:
     """The default method of calling the wrapper subprocess.
@@ -84,8 +95,8 @@ def default_subprocess_runner(
 
 
 def quiet_subprocess_runner(
-    cmd: Sequence[str],
-    cwd: Optional[str] = None,
+    cmd: Sequence[StrPath],
+    cwd: Optional[StrPath] = None,
     extra_environ: Optional[Mapping[str, str]] = None,
 ) -> None:
     """Call the subprocess while suppressing output.
@@ -99,7 +110,7 @@ def quiet_subprocess_runner(
     check_output(cmd, cwd=cwd, env=env, stderr=STDOUT)
 
 
-def norm_and_check(source_tree: str, requested: str) -> str:
+def norm_and_check(source_tree: StrPath, requested: StrPath) -> str:
     """Normalise and check a backend path.
 
     Ensure that the requested backend path is specified as a relative path,
@@ -128,11 +139,11 @@ class BuildBackendHookCaller:
 
     def __init__(
         self,
-        source_dir: str,
+        source_dir: StrPath,
         build_backend: str,
-        backend_path: Optional[Sequence[str]] = None,
+        backend_path: Optional[Sequence[StrPath]] = None,
         runner: Optional["SubprocessRunner"] = None,
-        python_executable: Optional[str] = None,
+        python_executable: Optional[StrPath] = None,
     ) -> None:
         """
         :param source_dir: The source directory to invoke the build backend for
@@ -147,9 +158,11 @@ def __init__(
 
         self.source_dir = abspath(source_dir)
         self.build_backend = build_backend
-        if backend_path:
-            backend_path = [norm_and_check(self.source_dir, p) for p in backend_path]
-        self.backend_path = backend_path
+        self.backend_path: Optional[List[str]] = (
+            [norm_and_check(self.source_dir, p) for p in backend_path]
+            if backend_path is not None
+            else None
+        )
         self._subprocess_runner = runner
         if not python_executable:
             python_executable = sys.executable
@@ -199,7 +212,7 @@ def get_requires_for_build_wheel(
 
     def prepare_metadata_for_build_wheel(
         self,
-        metadata_directory: str,
+        metadata_directory: StrPath,
         config_settings: Optional[Mapping[str, Any]] = None,
         _allow_fallback: bool = True,
     ) -> str:
@@ -232,9 +245,9 @@ def prepare_metadata_for_build_wheel(
 
     def build_wheel(
         self,
-        wheel_directory: str,
+        wheel_directory: StrPath,
         config_settings: Optional[Mapping[str, Any]] = None,
-        metadata_directory: Optional[str] = None,
+        metadata_directory: Optional[StrPath] = None,
     ) -> str:
         """Build a wheel from this project.
 
@@ -282,7 +295,7 @@ def get_requires_for_build_editable(
 
     def prepare_metadata_for_build_editable(
         self,
-        metadata_directory: str,
+        metadata_directory: StrPath,
         config_settings: Optional[Mapping[str, Any]] = None,
         _allow_fallback: bool = True,
     ) -> Optional[str]:
@@ -314,9 +327,9 @@ def prepare_metadata_for_build_editable(
 
     def build_editable(
         self,
-        wheel_directory: str,
+        wheel_directory: StrPath,
         config_settings: Optional[Mapping[str, Any]] = None,
-        metadata_directory: Optional[str] = None,
+        metadata_directory: Optional[StrPath] = None,
     ) -> str:
         """Build an editable wheel from this project.
 
@@ -359,7 +372,7 @@ def get_requires_for_build_sdist(
 
     def build_sdist(
         self,
-        sdist_directory: str,
+        sdist_directory: StrPath,
         config_settings: Optional[Mapping[str, Any]] = None,
     ) -> str:
         """Build an sdist from this project.