refactor: Move preset checking into ui.Theme()

Author: gadenbuie

shiny/ui/_theme.py

@@ -131,12 +131,11 @@ def server(input):
 
     def __init__(
         self,
-        preset: ShinyThemePreset = "shiny",
+        preset: str | None = None,
         name: Optional[str] = None,
         include_paths: Optional[str | pathlib.Path | list[str | pathlib.Path]] = None,
     ):
-        check_is_valid_preset(preset)
-        self._preset: ShinyThemePreset = preset
+        self._preset: ShinyThemePreset = check_is_valid_preset(preset or "shiny")
         self.name = name
         # 2024-06-21: `version` is not exposed because we currently support only BS 5.
         # In the future, the Bootstrap version could be chosen by the user on init.
@@ -556,13 +555,15 @@ def path_pkg_preset(preset: ShinyThemePreset, *args: str) -> str:
     return pathlib.Path(path).as_posix()
 
 
-def check_is_valid_preset(preset: ShinyThemePreset) -> None:
+def check_is_valid_preset(preset: str | None) -> ShinyThemePreset:
     if preset not in shiny_theme_presets:
         raise ValueError(
             f"Invalid preset '{preset}'.\n"
             + f"""Expected one of: "{'", "'.join(shiny_theme_presets)}".""",
         )
 
+    return preset
+
 
 def check_theme_pkg_installed(pkg: str, spec: str | None = None) -> None:
     import importlib.util

shiny/ui/_theme_brand.py

@@ -11,7 +11,6 @@
 
 from .._versions import bootstrap as v_bootstrap
 from ._theme import Theme
-from ._theme_presets import ShinyThemePreset, shiny_theme_presets
 from .css import CssUnit, as_css_unit
 
 YamlScalarType = Union[str, int, bool, float, None]
@@ -185,7 +184,7 @@ class BrandBootstrapConfig:
     def __init__(
         self,
         version: Any = v_bootstrap,
-        preset: Any = "shiny",
+        preset: str | None = None,
         functions: str | None = None,
         defaults: dict[str, YamlScalarType] | None = None,
         mixins: str | None = None,
@@ -208,14 +207,8 @@ def __init__(
             )
             v_major = bs_major
 
-        if not isinstance(preset, str) or preset not in shiny_theme_presets:
-            raise ValueError(
-                f"{preset!r} is not a valid Bootstrap preset provided by Shiny. "
-                f"Valid presets are {shiny_theme_presets}."
-            )
-
         self.version = v_major
-        self.preset: ShinyThemePreset = preset
+        self.preset = preset
         self.functions = functions
         self.defaults = defaults
         self.mixins = mixins
@@ -236,7 +229,7 @@ def from_brand(cls, brand: Brand):
 
         return cls(
             version=d_shiny.version or d_bootstrap.version or v_bootstrap,
-            preset=d_shiny.preset or d_bootstrap.preset or "shiny",
+            preset=d_shiny.preset or d_bootstrap.preset,
             functions=d_shiny.functions,
             defaults=defaults,
             mixins=d_shiny.mixins,