Fixed crash in Python 3.15.0a6

The crash was caused by changes in the argparse internal API in Python 3.15, specifically in how it handles colorization and formatter initialization.

Changes Made:

1. Cmd2HelpFormatter._set_color: Added an override for the _set_color method to handle the new file keyword argument introduced in Python 3.15. It uses a try-except block to fall back to the older signature if the underlying RichHelpFormatter (from rich-argparse) does not yet support the new keyword argument.

2. Cmd2ArgumentParser._get_formatter: Updated the _get_formatter method to accept **kwargs and pass them to the superclass. This is necessary because Python 3.15's argparse now passes a file argument to this method in several places (e.g., print_usage).

3. TextGroup.__init__: Updated the type hint for the formatter_creator parameter from Callable[[], Cmd2HelpFormatter] to Callable[..., Cmd2HelpFormatter] to remain consistent with the updated _get_formatter signature.

Author: tleonhardt

cmd2/argparse_custom.py

@@ -1030,6 +1030,18 @@ def console(self, console: Cmd2RichArgparseConsole) -> None:
         """Set our console instance."""
         self._console = console
 
+    def _set_color(self, color: bool, **kwargs: Any) -> None:
+        """Set the color for the help output.
+
+        This override is needed because Python 3.15 added a 'file' keyword argument
+        to _set_color() which some versions of RichHelpFormatter don't support.
+        """
+        try:
+            super()._set_color(color, **kwargs)
+        except TypeError:
+            # Fallback for older versions of RichHelpFormatter that don't support keyword arguments
+            super()._set_color(color)
+
     def _build_nargs_range_str(self, nargs_range: tuple[int, int | float]) -> str:
         """Generate nargs range string for help text."""
         if nargs_range[1] == constants.INFINITY:
@@ -1134,7 +1146,7 @@ def __init__(
         self,
         title: str,
         text: RenderableType,
-        formatter_creator: Callable[[], Cmd2HelpFormatter],
+        formatter_creator: Callable[..., Cmd2HelpFormatter],
     ) -> None:
         """TextGroup initializer.
 
@@ -1258,9 +1270,9 @@ def error(self, message: str) -> NoReturn:
 
         self.exit(2, f'{formatted_message}\n')
 
-    def _get_formatter(self) -> Cmd2HelpFormatter:
+    def _get_formatter(self, **kwargs: Any) -> Cmd2HelpFormatter:
         """Override with customizations for Cmd2HelpFormatter."""
-        return cast(Cmd2HelpFormatter, super()._get_formatter())
+        return cast(Cmd2HelpFormatter, super()._get_formatter(**kwargs))
 
     def format_help(self) -> str:
         """Override to add a newline."""