Use features new to Python 3.8, apply positional-only args

(the latter constitutes a breaking change for MkDocs, but nobody should be relying on these as named args)

mkdocs/commands/build.py

@@ -353,8 +353,7 @@ def build(
         # Run `post_build` plugin events.
         config.plugins.on_post_build(config=config)
 
-        counts = warning_counter.get_counts()
-        if counts:
+        if counts := warning_counter.get_counts():
             msg = ', '.join(f'{v} {k.lower()}s' for k, v in counts)
             raise Abort(f'Aborted with {msg} in strict mode!')
 

mkdocs/config/base.py

@@ -51,7 +51,7 @@ class BaseConfigOption(Generic[T]):
     def default(self, value):
         self._default = value
 
-    def validate(self, value: object) -> T:
+    def validate(self, value: object, /) -> T:
         return self.run_validation(value)
 
     def reset_warnings(self) -> None:
@@ -64,7 +64,7 @@ class BaseConfigOption(Generic[T]):
         The pre-validation process method should be implemented by subclasses.
         """
 
-    def run_validation(self, value: object):
+    def run_validation(self, value: object, /):
         """
         Perform validation for a value.
 

mkdocs/config/config_options.py

@@ -65,7 +65,7 @@ class SubConfig(Generic[SomeConfig], BaseConfigOption[SomeConfig]):
 
     @overload
     def __init__(
-        self: SubConfig[SomeConfig], config_class: type[SomeConfig], *, validate: bool = True
+        self: SubConfig[SomeConfig], config_class: type[SomeConfig], /, *, validate: bool = True
     ):
         """Create a sub-config in a type-safe way, using fields defined in a Config subclass."""
 
@@ -324,14 +324,14 @@ class Type(Generic[T], OptionallyRequired[T]):
     """
 
     @overload
-    def __init__(self, type_: type[T], length: int | None = None, **kwargs):
+    def __init__(self, type_: type[T], /, length: int | None = None, **kwargs):
         ...
 
     @overload
-    def __init__(self, type_: tuple[type[T], ...], length: int | None = None, **kwargs):
+    def __init__(self, type_: tuple[type[T], ...], /, length: int | None = None, **kwargs):
         ...
 
-    def __init__(self, type_, length=None, **kwargs) -> None:
+    def __init__(self, type_, /, length=None, **kwargs) -> None:
         super().__init__(**kwargs)
         self._type = type_
         self.length = length
@@ -700,7 +700,7 @@ class FilesystemObject(Type[str]):
     name = 'file or directory'
 
     def __init__(self, exists: bool = False, **kwargs) -> None:
-        super().__init__(type_=str, **kwargs)
+        super().__init__(str, **kwargs)
         self.exists = exists
         self.config_dir: str | None = None
 

mkdocs/livereload/__init__.py

@@ -254,8 +254,7 @@ class LiveReloadServer(socketserver.ThreadingMixIn, wsgiref.simple_server.WSGISe
         path = environ["PATH_INFO"].encode("latin-1").decode("utf-8", "ignore")
 
         if path.startswith("/livereload/"):
-            m = re.fullmatch(r"/livereload/([0-9]+)/[0-9]+", path)
-            if m:
+            if m := re.fullmatch(r"/livereload/([0-9]+)/[0-9]+", path):
                 epoch = int(m[1])
                 start_response("200 OK", [("Content-Type", "text/plain")])
 

mkdocs/structure/nav.py

@@ -193,8 +193,7 @@ def _data_to_navigation(data, files: Files, config: MkDocsConfig):
             for item in data
         ]
     title, path = data if isinstance(data, tuple) else (None, data)
-    file = files.get_file_from_path(path)
-    if file:
+    if file := files.get_file_from_path(path):
         if file.inclusion.is_excluded():
             log.log(
                 min(logging.INFO, config.validation.nav.not_found),

mkdocs/tests/build_tests.py

@@ -805,8 +805,7 @@ class _TestPreprocessor(markdown.preprocessors.Preprocessor):
 
     def run(self, lines: list[str]) -> list[str]:
         for i, line in enumerate(lines):
-            m = re.search(r'^--8<-- "(.+)"$', line)
-            if m:
+            if m := re.search(r'^--8<-- "(.+)"$', line):
                 try:
                     lines[i] = Path(self.base_path, m[1]).read_text()
                 except OSError:

mkdocs/theme.py

@@ -134,8 +134,7 @@ class Theme(MutableMapping[str, Any]):
 
         log.debug(f"Loaded theme configuration for '{name}' from '{file_path}': {theme_config}")
 
-        parent_theme = theme_config.pop('extends', None)
-        if parent_theme:
+        if parent_theme := theme_config.pop('extends', None):
             themes = utils.get_theme_names()
             if parent_theme not in themes:
                 raise ValidationError(

mkdocs/utils/meta.py

@@ -62,8 +62,7 @@ def get_data(doc: str) -> tuple[str, dict[str, Any]]:
     data = {}
 
     # First try YAML
-    m = YAML_RE.match(doc)
-    if m:
+    if m := YAML_RE.match(doc):
         try:
             data = yaml.load(m.group(1), SafeLoader)
             if isinstance(data, dict):
@@ -83,8 +82,7 @@ def get_data(doc: str) -> tuple[str, dict[str, Any]]:
 
         if line.strip() == '':
             break  # blank line - done
-        m1 = META_RE.match(line)
-        if m1:
+        if m1 := META_RE.match(line):
             key = m1.group('key').lower().strip()
             value = m1.group('value').strip()
             if key in data: