refactor: extract styles configuration to separate method (hynek#741)

* refactor: extract styles configuration to separate method

Extract the styles configuration logic from ConsoleRenderer.__init__
into a dedicated configure_styles class method. This improves code
readability and makes the styles setup logic reusable and testable.

- Move colorama initialization and styles selection to configure_styles()
- Add comprehensive docstring with args, returns, and raises sections
- Remove noqa comment as method complexity is now reduced
- Maintain existing behavior for colors and force_colors parameters

* docs, tests

* docs: versionadded

* docs: changelog.md

* fix: _Styles -> Styles

* Fix type

`Styles` already includes `Type[_Styles]`, so `type[Styles]` should be
wrong

* Fix Sphinx build

---------

Co-authored-by: Hynek Schlawack <hs@ox.cx>

Author: HairlessVillager

CHANGELOG.md

@@ -17,6 +17,9 @@ You can find our backwards-compatibility policy [here](https://github.com/hynek/
 
 ### Added
 
+- Added `structlog.dev.ConsoleRenderer.get_default_column_styles` for reuse the default column styles.
+  [#741](https://github.com/hynek/structlog/pull/741)
+
 - `structlog.testing.capture_logs()` now optionally accepts *processors* to apply before capture.
   [#728](https://github.com/hynek/structlog/pull/728)
 

docs/api.rst

@@ -76,7 +76,7 @@ API Reference
 .. automodule:: structlog.dev
 
 .. autoclass:: ConsoleRenderer
-   :members: get_default_level_styles
+   :members: get_default_level_styles, get_default_column_styles
 
 .. autoclass:: Column
 .. autoclass:: ColumnFormatter(typing.Protocol)

docs/conf.py

@@ -83,6 +83,7 @@
     ("py:class", "PlainFileObserver"),
     ("py:class", "Processor"),
     ("py:class", "Styles"),
+    ("py:class", "structlog.dev._Styles"),
     ("py:class", "WrappedLogger"),
     ("py:class", "structlog.threadlocal.TLLogger"),
     ("py:class", "structlog.typing.EventDict"),

src/structlog/dev.py

@@ -567,7 +567,7 @@ class ConsoleRenderer:
     .. versionadded:: 24.2.0 *pad_level*
     """
 
-    def __init__(  # noqa: PLR0912, PLR0915
+    def __init__(
         self,
         pad_event: int = _EVENT_WIDTH,
         colors: bool = _has_colors,
@@ -630,29 +630,7 @@ def add_meaningless_arg(arg: str) -> None:
             return
 
         # Create default columns configuration.
-        styles: Styles
-        if colors:
-            if _IS_WINDOWS:  # pragma: no cover
-                # On Windows, we can't do colorful output without colorama.
-                if colorama is None:
-                    classname = self.__class__.__name__
-                    raise SystemError(
-                        _MISSING.format(
-                            who=classname + " with `colors=True`",
-                            package="colorama",
-                        )
-                    )
-                # Colorama must be init'd on Windows, but must NOT be
-                # init'd on other OSes, because it can break colors.
-                if force_colors:
-                    colorama.deinit()
-                    colorama.init(strip=False)
-                else:
-                    colorama.init()
-
-            styles = _ColorfulStyles
-        else:
-            styles = _PlainStyles
+        styles = self.get_default_column_styles(colors, force_colors)
 
         self._styles = styles
 
@@ -719,6 +697,53 @@ def add_meaningless_arg(arg: str) -> None:
             Column("logger_name", logger_name_formatter),
         ]
 
+    @classmethod
+    def get_default_column_styles(
+        cls, colors: bool = _has_colors, force_colors: bool = False
+    ) -> Styles:
+        """
+        Configure and return the appropriate styles class for console output.
+
+        This method handles the setup of colorful or plain styles, including
+        proper colorama initialization on Windows systems when colors are enabled.
+
+        Args:
+            colors: Whether to use colorful output styles.
+
+            force_colors:
+                Force colorful output even in non-interactive environments.
+                Only relevant on Windows with colorama.
+
+        Returns:
+            The configured styles class (_ColorfulStyles or _PlainStyles).
+
+        Raises:
+            SystemError: On Windows when colors=True but colorama is not installed.
+
+        .. versionadded:: 25.5.0
+        """
+        if not colors:
+            return _PlainStyles
+
+        if _IS_WINDOWS:  # pragma: no cover
+            # On Windows, we can't do colorful output without colorama.
+            if colorama is None:
+                raise SystemError(
+                    _MISSING.format(
+                        who=cls.__name__ + " with `colors=True`",
+                        package="colorama",
+                    )
+                )
+            # Colorama must be init'd on Windows, but must NOT be
+            # init'd on other OSes, because it can break colors.
+            if force_colors:
+                colorama.deinit()
+                colorama.init(strip=False)
+            else:
+                colorama.init()
+
+        return _ColorfulStyles
+
     def _repr(self, val: Any) -> str:
         """
         Determine representation of *val* depending on its type &

tests/test_dev.py

@@ -175,6 +175,64 @@ def test_init_accepts_overriding_levels(self, styles, padded):
             + styles.reset
         ) == rv
 
+    def test_returns_colorful_styles_when_colors_true(self):
+        """
+        When colors=True, returns _ColorfulStyles class.
+        """
+        styles = dev.ConsoleRenderer.get_default_column_styles(colors=True)
+
+        assert styles is dev._ColorfulStyles
+        assert hasattr(styles, "reset")
+        assert hasattr(styles, "bright")
+        assert hasattr(styles, "level_critical")
+        assert hasattr(styles, "kv_key")
+        assert hasattr(styles, "kv_value")
+
+    def test_returns_plain_styles_when_colors_false(self):
+        """
+        When colors=False, returns _PlainStyles class.
+        """
+        styles = dev.ConsoleRenderer.get_default_column_styles(colors=False)
+
+        assert styles is dev._PlainStyles
+        assert styles.reset == ""
+        assert styles.bright == ""
+        assert styles.level_critical == ""
+        assert styles.kv_key == ""
+        assert styles.kv_value == ""
+
+    @pytest.mark.skipif(
+        not dev._IS_WINDOWS or dev.colorama is not None,
+        reason="Only relevant on Windows without colorama",
+    )
+    def test_raises_system_error_on_windows_without_colorama(self):
+        """
+        On Windows without colorama, raises SystemError when colors=True.
+        """
+        with pytest.raises(SystemError, match="requires the colorama package"):
+            dev.ConsoleRenderer.get_default_column_styles(colors=True)
+
+    @pytest.mark.skipif(
+        not dev._IS_WINDOWS or dev.colorama is None,
+        reason="Only relevant on Windows with colorama",
+    )
+    def test_initializes_colorama_on_windows_with_force_colors(self):
+        """
+        On Windows with colorama, force_colors=True reinitializes colorama.
+        """
+        with mock.patch.object(
+            dev.colorama, "init"
+        ) as mock_init, mock.patch.object(
+            dev.colorama, "deinit"
+        ) as mock_deinit:
+            styles = dev.ConsoleRenderer.get_default_column_styles(
+                colors=True, force_colors=True
+            )
+
+            assert styles is dev._ColorfulStyles
+            mock_deinit.assert_called_once()
+            mock_init.assert_called_once_with(strip=False)
+
     def test_logger_name(self, cr, styles, padded):
         """
         Logger names are appended after the event.