Added cmd2.Cmd method to determine what ArgparseCompleter type to use

Author: kmvanbrunt

cmd2/argparse_completer.py

@@ -408,11 +408,7 @@ def update_mutex_groups(arg_action: argparse.Action) -> None:
                                     parent_tokens[action.dest] = [token]
 
                                 parser: argparse.ArgumentParser = self._subcommand_action.choices[token]
-                                completer_type: Optional[
-                                    Type[ArgparseCompleter]
-                                ] = parser.get_ap_completer_type()  # type: ignore[attr-defined]
-                                if completer_type is None:
-                                    completer_type = DEFAULT_AP_COMPLETER
+                                completer_type = self._cmd2_app._determine_ap_completer_type(parser)
 
                                 completer = completer_type(parser, self._cmd2_app, parent_tokens=parent_tokens)
 
@@ -616,11 +612,7 @@ def complete_subcommand_help(self, text: str, line: str, begidx: int, endidx: in
             for token_index, token in enumerate(tokens):
                 if token in self._subcommand_action.choices:
                     parser: argparse.ArgumentParser = self._subcommand_action.choices[token]
-                    completer_type: Optional[
-                        Type[ArgparseCompleter]
-                    ] = parser.get_ap_completer_type()  # type: ignore[attr-defined]
-                    if completer_type is None:
-                        completer_type = DEFAULT_AP_COMPLETER
+                    completer_type = self._cmd2_app._determine_ap_completer_type(parser)
 
                     completer = completer_type(parser, self._cmd2_app)
                     return completer.complete_subcommand_help(text, line, begidx, endidx, tokens[token_index + 1 :])
@@ -643,11 +635,7 @@ def format_help(self, tokens: List[str]) -> str:
             for token_index, token in enumerate(tokens):
                 if token in self._subcommand_action.choices:
                     parser: argparse.ArgumentParser = self._subcommand_action.choices[token]
-                    completer_type: Optional[
-                        Type[ArgparseCompleter]
-                    ] = parser.get_ap_completer_type()  # type: ignore[attr-defined]
-                    if completer_type is None:
-                        completer_type = DEFAULT_AP_COMPLETER
+                    completer_type = self._cmd2_app._determine_ap_completer_type(parser)
 
                     completer = completer_type(parser, self._cmd2_app)
                     return completer.format_help(tokens[token_index + 1 :])

cmd2/cmd2.py

@@ -1841,6 +1841,23 @@ def _display_matches_pyreadline(self, matches: List[str]) -> None:  # pragma: no
                 # Display matches using actual display function. This also redraws the prompt and input lines.
                 orig_pyreadline_display(matches_to_display)
 
+    @staticmethod
+    def _determine_ap_completer_type(parser: argparse.ArgumentParser) -> Type[argparse_completer.ArgparseCompleter]:
+        """
+        Determine what type of ArgparseCompleter to use on a given parser. If the parser does not have one
+        set, then use argparse_completer.DEFAULT_AP_COMPLETER.
+
+        :param parser: the parser to examine
+        :return: type of ArgparseCompleter
+        """
+        completer_type: Optional[
+            Type[argparse_completer.ArgparseCompleter]
+        ] = parser.get_ap_completer_type()  # type: ignore[attr-defined]
+
+        if completer_type is None:
+            completer_type = argparse_completer.DEFAULT_AP_COMPLETER
+        return completer_type
+
     def _perform_completion(
         self, text: str, line: str, begidx: int, endidx: int, custom_settings: Optional[utils.CustomCompletionSettings] = None
     ) -> None:
@@ -1910,9 +1927,7 @@ def _perform_completion(
                         cmd_set = self._cmd_to_command_sets[command] if command in self._cmd_to_command_sets else None
 
                         # Create the argparse completer
-                        completer_type = argparser.get_ap_completer_type()  # type: ignore[attr-defined]
-                        if completer_type is None:
-                            completer_type = argparse_completer.DEFAULT_AP_COMPLETER
+                        completer_type = self._determine_ap_completer_type(argparser)
                         completer = completer_type(argparser, self)
 
                         completer_func = functools.partial(
@@ -1932,9 +1947,7 @@ def _perform_completion(
         # Otherwise we are completing the command token or performing custom completion
         else:
             # Create the argparse completer
-            completer_type = custom_settings.parser.get_ap_completer_type()  # type: ignore[attr-defined]
-            if completer_type is None:
-                completer_type = argparse_completer.DEFAULT_AP_COMPLETER
+            completer_type = self._determine_ap_completer_type(custom_settings.parser)
             completer = completer_type(custom_settings.parser, self)
 
             completer_func = functools.partial(