style: clarify .py file path argument names

- `relative_path`: path relative to a `root` directory
- `path_from_cwd`: either relative to working directory
  or an absolute path

src/darker/import_sorting.py

@@ -54,7 +54,7 @@ class IsortArgs(TypedDict, total=False):
 
 def apply_isort(  # pylint: disable=too-many-arguments  # noqa: PLR0913
     content: TextDocument,
-    src: Path,
+    relative_path: Path,
     root: Path,
     exclude: Collection[str],
     edited_linenums_differ: EditedLinenumsDiffer,
@@ -64,9 +64,9 @@ def apply_isort(  # pylint: disable=too-many-arguments  # noqa: PLR0913
     """Run isort on the given Python source file content
 
     :param content: The contents of the Python source code file to sort imports in
-    :param src: The path to the file relative to ``root``. Note that this may differ
-                from the path given on the command line in
-                case of VSCode temporary files.
+    :param relative_path: The path to the file relative to ``root``. Note that this may
+                          differ from the path given on the command line in case of
+                          VSCode temporary files.
     :param root: The root directory based on which ``src`` is resolved.
     :param exclude: The file path patterns to exclude from import sorting
     :param edited_linenums_differ: Helper for finding out which lines were edited
@@ -75,17 +75,17 @@ def apply_isort(  # pylint: disable=too-many-arguments  # noqa: PLR0913
     :return: Original Python source file contents with imports sorted
 
     """
-    if glob_any(src, exclude):
+    if glob_any(relative_path, exclude):
         return content
     edited_linenums = edited_linenums_differ.revision_vs_lines(
-        src,
+        relative_path,
         content,
         context_lines=0,
     )  # pylint: disable=duplicate-code
     if not edited_linenums:
         return content
-    isort_args = _build_isort_args(root / src, config, line_length)
-    rev2_isorted = _call_isort_code(content, root / src, isort_args)
+    isort_args = _build_isort_args(root / relative_path, config, line_length)
+    rev2_isorted = _call_isort_code(content, root / relative_path, isort_args)
     # Get the chunks in the diff between the edited and import-sorted file
     isort_chunks = diff_chunks(content, rev2_isorted)
     if not isort_chunks:
@@ -101,16 +101,16 @@ def apply_isort(  # pylint: disable=too-many-arguments  # noqa: PLR0913
 
 
 def _build_isort_args(
-    src: Path,
+    path_from_cwd: Path,
     config: Optional[str] = None,
     line_length: Optional[int] = None,
 ) -> IsortArgs:
     """Build ``isort.code()`` keyword arguments
 
-    :param src: The path to the file. This must be either an absolute path or a relative
-                path from the current working directory. Note that this may differ from
-                the path given on the command line in
-                case of VSCode temporary files.
+    :param path_from_cwd: The path to the file. This must be either an absolute path or
+                          a relative path from the current working directory. Note that
+                          this may differ from the path given on the command line in
+                          case of VSCode temporary files.
     :param config: Path to configuration file
     :param line_length: Maximum line length to use
 
@@ -119,19 +119,20 @@ def _build_isort_args(
     if config:
         isort_args["settings_file"] = config
     else:
-        isort_args["settings_path"] = str(find_project_root((str(src),)))
+        isort_args["settings_path"] = str(find_project_root((str(path_from_cwd),)))
     if line_length:
         isort_args["line_length"] = line_length
     return isort_args
 
 
 def _call_isort_code(
-    content: TextDocument, src: Path, isort_args: IsortArgs
+    content: TextDocument, path_from_cwd: Path, isort_args: IsortArgs
 ) -> TextDocument:
     """Call ``isort.code()`` and return the result as a `TextDocument` object
 
     :param content: The contents of the Python source code file to sort imports in
-    :param src: The path to the file with the given content
+    :param path_from_cwd: The path to the file with the given content, either relative
+                          to the current working directory or an absolute path.
     :param isort_args: Keyword arguments for ``isort.code()``
 
     """
@@ -141,7 +142,7 @@ def _call_isort_code(
         ", ".join(f"{k}={v!r}" for k, v in isort_args.items()),
     )
     with suppress(isort.exceptions.FileSkipped):
-        code = isort_code(code=code, file_path=src, **isort_args)
+        code = isort_code(code=code, file_path=path_from_cwd, **isort_args)
     return TextDocument.from_str(
         code,
         encoding=content.encoding,