Changed with_argparser() and as_subcommand_to() to accept either an ArgumentParser or a

factory callable that returns an ArgumentParser.
Changed Cmd constructor to construct an instance-specific ArgumentParser using either the factory callable
or by deep-copying the provided ArgumentParser.
With this change a new argparse instance should be created for each instance of Cmd.

Addresses #1002

Author: anselor

cmd2/cmd2.py

@@ -30,6 +30,7 @@
 # setting is True
 import argparse
 import cmd
+import copy
 import functools
 import glob
 import inspect
@@ -140,6 +141,7 @@
 from .utils import (
     Settable,
     get_defining_class,
+    is_callable,
     strip_doc_annotations,
     suggest_similar,
 )
@@ -510,6 +512,16 @@ def __init__(
         # This does not affect self.formatted_completions.
         self.matches_sorted = False
 
+        # Command parsers for this Cmd instance.
+        self._command_parsers: Dict[str, argparse.ArgumentParser] = {}
+
+        # Locates the command parser template or factory and creates an instance-specific parser
+        for command in self.get_all_commands():
+            self._register_command_parser(command, self.cmd_func(command))  # type: ignore[arg-type]
+
+        # Add functions decorated to be subcommands
+        self._register_subcommands(self)
+
         ############################################################################################################
         # The following code block loads CommandSets, verifies command names, and registers subcommands.
         # This block should appear after all attributes have been created since the registration code
@@ -529,9 +541,6 @@ def __init__(
             if not valid:
                 raise ValueError(f"Invalid command name '{cur_cmd}': {errmsg}")
 
-        # Add functions decorated to be subcommands
-        self._register_subcommands(self)
-
         self.suggest_similar_command = suggest_similar_command
         self.default_suggestion_message = "Did you mean {}?"
 
@@ -659,6 +668,43 @@ def register_command_set(self, cmdset: CommandSet) -> None:
             cmdset.on_unregistered()
             raise
 
+    def _build_parser(self, parent: Union['Cmd', CommandSet], parser_builder: Any) -> Optional[argparse.ArgumentParser]:
+        parser: Optional[argparse.ArgumentParser] = None
+        if is_callable(parser_builder):
+            if isinstance(parser_builder, staticmethod):
+                parser = cast(argparse.ArgumentParser, parser_builder.__func__())
+            elif isinstance(parser_builder, classmethod):
+                parser = cast(argparse.ArgumentParser, parser_builder.__func__(parent if not None else self))
+            else:
+                parser = cast(argparse.ArgumentParser, parser_builder())  # type: ignore[misc]
+        elif isinstance(parser_builder, argparse.ArgumentParser):
+            if sys.version_info >= (3, 6, 4):
+                parser = copy.deepcopy(parser_builder)
+            else:  # pragma: no cover
+                parser = parser_builder
+        return parser
+
+    def _register_command_parser(self, command: str, command_method: Callable[..., Any]) -> None:
+        if command not in self._command_parsers:
+            parser_builder = getattr(command_method, constants.CMD_ATTR_ARGPARSER, None)
+            parent = self.find_commandset_for_command(command) or self
+            parser = self._build_parser(parent, parser_builder)
+            if parser is None:
+                return
+
+            # argparser defaults the program name to sys.argv[0], but we want it to be the name of our command
+            from .decorators import (
+                _set_parser_prog,
+            )
+
+            _set_parser_prog(parser, command)
+
+            # If the description has not been set, then use the method docstring if one exists
+            if parser.description is None and hasattr(command_method, '__wrapped__') and command_method.__wrapped__.__doc__:
+                parser.description = strip_doc_annotations(command_method.__wrapped__.__doc__)
+
+            self._command_parsers[command] = parser
+
     def _install_command_function(self, command: str, command_wrapper: Callable[..., Any], context: str = '') -> None:
         cmd_func_name = COMMAND_FUNC_PREFIX + command
 
@@ -681,6 +727,8 @@ def _install_command_function(self, command: str, command_wrapper: Callable[...,
             self.pwarning(f"Deleting macro '{command}' because it shares its name with a new command")
             del self.macros[command]
 
+        self._register_command_parser(command, command_wrapper)
+
         setattr(self, cmd_func_name, command_wrapper)
 
     def _install_completer_function(self, cmd_name: str, cmd_completer: CompleterFunc) -> None:
@@ -727,6 +775,8 @@ def unregister_command_set(self, cmdset: CommandSet) -> None:
                     del self._cmd_to_command_sets[cmd_name]
 
                 delattr(self, COMMAND_FUNC_PREFIX + cmd_name)
+                if cmd_name in self._command_parsers:
+                    del self._command_parsers[cmd_name]
 
                 if hasattr(self, COMPLETER_FUNC_PREFIX + cmd_name):
                     delattr(self, COMPLETER_FUNC_PREFIX + cmd_name)
@@ -746,14 +796,7 @@ def _check_uninstallable(self, cmdset: CommandSet) -> None:
 
         for method in methods:
             command_name = method[0][len(COMMAND_FUNC_PREFIX) :]
-
-            # Search for the base command function and verify it has an argparser defined
-            if command_name in self.disabled_commands:
-                command_func = self.disabled_commands[command_name].command_function
-            else:
-                command_func = self.cmd_func(command_name)
-
-            command_parser = cast(argparse.ArgumentParser, getattr(command_func, constants.CMD_ATTR_ARGPARSER, None))
+            command_parser = self._command_parsers.get(command_name, None)
 
             def check_parser_uninstallable(parser: argparse.ArgumentParser) -> None:
                 for action in parser._actions:
@@ -792,7 +835,7 @@ def _register_subcommands(self, cmdset: Union[CommandSet, 'Cmd']) -> None:
         for method_name, method in methods:
             subcommand_name: str = getattr(method, constants.SUBCMD_ATTR_NAME)
             full_command_name: str = getattr(method, constants.SUBCMD_ATTR_COMMAND)
-            subcmd_parser = getattr(method, constants.CMD_ATTR_ARGPARSER)
+            subcmd_parser_builder = getattr(method, constants.CMD_ATTR_ARGPARSER)
 
             subcommand_valid, errmsg = self.statement_parser.is_valid_command(subcommand_name, is_subcommand=True)
             if not subcommand_valid:
@@ -812,7 +855,7 @@ def _register_subcommands(self, cmdset: Union[CommandSet, 'Cmd']) -> None:
                 raise CommandSetRegistrationError(
                     f"Could not find command '{command_name}' needed by subcommand: {str(method)}"
                 )
-            command_parser = getattr(command_func, constants.CMD_ATTR_ARGPARSER, None)
+            command_parser = self._command_parsers.get(command_name, None)
             if command_parser is None:
                 raise CommandSetRegistrationError(
                     f"Could not find argparser for command '{command_name}' needed by subcommand: {str(method)}"
@@ -832,16 +875,17 @@ def find_subcommand(action: argparse.ArgumentParser, subcmd_names: List[str]) ->
 
             target_parser = find_subcommand(command_parser, subcommand_names)
 
+            subcmd_parser = cast(argparse.ArgumentParser, self._build_parser(cmdset, subcmd_parser_builder))
+            from .decorators import (
+                _set_parser_prog,
+            )
+
+            _set_parser_prog(subcmd_parser, f'{command_name} {subcommand_name}')
+            if subcmd_parser.description is None and method.__doc__:
+                subcmd_parser.description = strip_doc_annotations(method.__doc__)
+
             for action in target_parser._actions:
                 if isinstance(action, argparse._SubParsersAction):
-                    # Temporary workaround for avoiding subcommand help text repeatedly getting added to
-                    # action._choices_actions. Until we have instance-specific parser objects, we will remove
-                    # any existing subcommand which has the same name before replacing it. This problem is
-                    # exercised when more than one cmd2.Cmd-based object is created and the same subcommands
-                    # get added each time. Argparse overwrites the previous subcommand but keeps growing the help
-                    # text which is shown by running something like 'alias -h'.
-                    action.remove_parser(subcommand_name)  # type: ignore[arg-type,attr-defined]
-
                     # Get the kwargs for add_parser()
                     add_parser_kwargs = getattr(method, constants.SUBCMD_ATTR_ADD_PARSER_KWARGS, {})
 
@@ -913,7 +957,7 @@ def _unregister_subcommands(self, cmdset: Union[CommandSet, 'Cmd']) -> None:
                 raise CommandSetRegistrationError(
                     f"Could not find command '{command_name}' needed by subcommand: {str(method)}"
                 )
-            command_parser = getattr(command_func, constants.CMD_ATTR_ARGPARSER, None)
+            command_parser = self._command_parsers.get(command_name, None)
             if command_parser is None:  # pragma: no cover
                 # This really shouldn't be possible since _register_subcommands would prevent this from happening
                 # but keeping in case it does for some strange reason
@@ -2034,7 +2078,7 @@ def _perform_completion(
                 else:
                     # There's no completer function, next see if the command uses argparse
                     func = self.cmd_func(command)
-                    argparser: Optional[argparse.ArgumentParser] = getattr(func, constants.CMD_ATTR_ARGPARSER, None)
+                    argparser = self._command_parsers.get(command, None)
 
                     if func is not None and argparser is not None:
                         # Get arguments for complete()
@@ -3259,14 +3303,19 @@ def _cmdloop(self) -> None:
     #############################################################
 
     # Top-level parser for alias
-    alias_description = "Manage aliases\n" "\n" "An alias is a command that enables replacement of a word by another string."
-    alias_epilog = "See also:\n" "  macro"
-    alias_parser = argparse_custom.DEFAULT_ARGUMENT_PARSER(description=alias_description, epilog=alias_epilog)
-    alias_subparsers = alias_parser.add_subparsers(dest='subcommand', metavar='SUBCOMMAND')
-    alias_subparsers.required = True
+    @staticmethod
+    def _build_alias_parser() -> argparse.ArgumentParser:
+        alias_description = (
+            "Manage aliases\n" "\n" "An alias is a command that enables replacement of a word by another string."
+        )
+        alias_epilog = "See also:\n" "  macro"
+        alias_parser = argparse_custom.DEFAULT_ARGUMENT_PARSER(description=alias_description, epilog=alias_epilog)
+        alias_subparsers = alias_parser.add_subparsers(dest='subcommand', metavar='SUBCOMMAND')
+        alias_subparsers.required = True
+        return alias_parser
 
     # Preserve quotes since we are passing strings to other commands
-    @with_argparser(alias_parser, preserve_quotes=True)
+    @with_argparser(_build_alias_parser, preserve_quotes=True)
     def do_alias(self, args: argparse.Namespace) -> None:
         """Manage aliases"""
         # Call handler for whatever subcommand was selected
@@ -3681,7 +3730,7 @@ def complete_help_subcommands(
 
         # Check if this command uses argparse
         func = self.cmd_func(command)
-        argparser = getattr(func, constants.CMD_ATTR_ARGPARSER, None)
+        argparser = self._command_parsers.get(command, None)
         if func is None or argparser is None:
             return []
 
@@ -3717,7 +3766,7 @@ def do_help(self, args: argparse.Namespace) -> None:
             # Getting help for a specific command
             func = self.cmd_func(args.command)
             help_func = getattr(self, constants.HELP_FUNC_PREFIX + args.command, None)
-            argparser = getattr(func, constants.CMD_ATTR_ARGPARSER, None)
+            argparser = self._command_parsers.get(args.command, None)
 
             # If the command function uses argparse, then use argparse's help
             if func is not None and argparser is not None:
@@ -3853,7 +3902,7 @@ def _build_command_info(self) -> Tuple[Dict[str, List[str]], List[str], List[str
                 help_topics.remove(command)
 
                 # Non-argparse commands can have help_functions for their documentation
-                if not hasattr(func, constants.CMD_ATTR_ARGPARSER):
+                if command not in self._command_parsers:
                     has_help_func = True
 
             if hasattr(func, constants.CMD_ATTR_HELP_CATEGORY):
@@ -3899,7 +3948,7 @@ def _print_topics(self, header: str, cmds: List[str], verbose: bool) -> None:
                     doc: Optional[str]
 
                     # Non-argparse commands can have help_functions for their documentation
-                    if not hasattr(cmd_func, constants.CMD_ATTR_ARGPARSER) and command in topics:
+                    if command not in self._command_parsers and command in topics:
                         help_func = getattr(self, constants.HELP_FUNC_PREFIX + command)
                         result = io.StringIO()
 

cmd2/decorators.py

@@ -12,6 +12,7 @@
     Tuple,
     TypeVar,
     Union,
+    overload,
 )
 
 from . import (
@@ -30,9 +31,6 @@
 from .parsing import (
     Statement,
 )
-from .utils import (
-    strip_doc_annotations,
-)
 
 if TYPE_CHECKING:  # pragma: no cover
     import cmd2
@@ -261,17 +259,39 @@ def _set_parser_prog(parser: argparse.ArgumentParser, prog: str) -> None:
 ]
 
 
+@overload
 def with_argparser(
     parser: argparse.ArgumentParser,
     *,
     ns_provider: Optional[Callable[..., argparse.Namespace]] = None,
     preserve_quotes: bool = False,
     with_unknown_args: bool = False,
+) -> Callable[[ArgparseCommandFunc[CommandParent]], RawCommandFuncOptionalBoolReturn[CommandParent]]:
+    ...  # pragma: no cover
+
+
+@overload
+def with_argparser(
+    parser: Callable[[], argparse.ArgumentParser],
+    *,
+    ns_provider: Optional[Callable[..., argparse.Namespace]] = None,
+    preserve_quotes: bool = False,
+    with_unknown_args: bool = False,
+) -> Callable[[ArgparseCommandFunc[CommandParent]], RawCommandFuncOptionalBoolReturn[CommandParent]]:
+    ...  # pragma: no cover
+
+
+def with_argparser(
+    parser: Union[argparse.ArgumentParser, Callable[[], argparse.ArgumentParser]],
+    *,
+    ns_provider: Optional[Callable[..., argparse.Namespace]] = None,
+    preserve_quotes: bool = False,
+    with_unknown_args: bool = False,
 ) -> Callable[[ArgparseCommandFunc[CommandParent]], RawCommandFuncOptionalBoolReturn[CommandParent]]:
     """A decorator to alter a cmd2 method to populate its ``args`` argument by parsing arguments
     with the given instance of argparse.ArgumentParser.
 
-    :param parser: unique instance of ArgumentParser
+    :param parser: unique instance of ArgumentParser or a callable that returns an ArgumentParser
     :param ns_provider: An optional function that accepts a cmd2.Cmd or cmd2.CommandSet object as an argument and returns an
                         argparse.Namespace. This is useful if the Namespace needs to be prepopulated with state data that
                         affects parsing.
@@ -339,6 +359,9 @@ def cmd_wrapper(*args: Any, **kwargs: Dict[str, Any]) -> Optional[bool]:
             statement, parsed_arglist = cmd2_app.statement_parser.get_command_arg_list(
                 command_name, statement_arg, preserve_quotes
             )
+            arg_parser = cmd2_app._command_parsers.get(command_name, None)
+            if arg_parser is None:
+                raise ValueError(f'No argument parser found for {command_name}')
 
             if ns_provider is None:
                 namespace = None
@@ -352,9 +375,9 @@ def cmd_wrapper(*args: Any, **kwargs: Dict[str, Any]) -> Optional[bool]:
             try:
                 new_args: Union[Tuple[argparse.Namespace], Tuple[argparse.Namespace, List[str]]]
                 if with_unknown_args:
-                    new_args = parser.parse_known_args(parsed_arglist, namespace)
+                    new_args = arg_parser.parse_known_args(parsed_arglist, namespace)
                 else:
-                    new_args = (parser.parse_args(parsed_arglist, namespace),)
+                    new_args = (arg_parser.parse_args(parsed_arglist, namespace),)
                 ns = new_args[0]
             except SystemExit:
                 raise Cmd2ArgparseError
@@ -374,16 +397,7 @@ def cmd_wrapper(*args: Any, **kwargs: Dict[str, Any]) -> Optional[bool]:
                 args_list = _arg_swap(args, statement_arg, *new_args)
                 return func(*args_list, **kwargs)  # type: ignore[call-arg]
 
-        # argparser defaults the program name to sys.argv[0], but we want it to be the name of our command
         command_name = func.__name__[len(constants.COMMAND_FUNC_PREFIX) :]
-        _set_parser_prog(parser, command_name)
-
-        # If the description has not been set, then use the method docstring if one exists
-        if parser.description is None and func.__doc__:
-            parser.description = strip_doc_annotations(func.__doc__)
-
-        # Set the command's help text as argparser.description (which can be None)
-        cmd_wrapper.__doc__ = parser.description
 
         # Set some custom attributes for this command
         setattr(cmd_wrapper, constants.CMD_ATTR_ARGPARSER, parser)
@@ -395,13 +409,37 @@ def cmd_wrapper(*args: Any, **kwargs: Dict[str, Any]) -> Optional[bool]:
     return arg_decorator
 
 
+@overload
 def as_subcommand_to(
     command: str,
     subcommand: str,
     parser: argparse.ArgumentParser,
     *,
     help: Optional[str] = None,
     aliases: Optional[List[str]] = None,
+) -> Callable[[ArgparseCommandFunc[CommandParent]], ArgparseCommandFunc[CommandParent]]:
+    ...  # pragma: no cover
+
+
+@overload
+def as_subcommand_to(
+    command: str,
+    subcommand: str,
+    parser: Callable[[], argparse.ArgumentParser],
+    *,
+    help: Optional[str] = None,
+    aliases: Optional[List[str]] = None,
+) -> Callable[[ArgparseCommandFunc[CommandParent]], ArgparseCommandFunc[CommandParent]]:
+    ...  # pragma: no cover
+
+
+def as_subcommand_to(
+    command: str,
+    subcommand: str,
+    parser: Union[argparse.ArgumentParser, Callable[[], argparse.ArgumentParser]],
+    *,
+    help: Optional[str] = None,
+    aliases: Optional[List[str]] = None,
 ) -> Callable[[ArgparseCommandFunc[CommandParent]], ArgparseCommandFunc[CommandParent]]:
     """
     Tag this method as a subcommand to an existing argparse decorated command.
@@ -417,12 +455,6 @@ def as_subcommand_to(
     """
 
     def arg_decorator(func: ArgparseCommandFunc[CommandParent]) -> ArgparseCommandFunc[CommandParent]:
-        _set_parser_prog(parser, command + ' ' + subcommand)
-
-        # If the description has not been set, then use the method docstring if one exists
-        if parser.description is None and func.__doc__:
-            parser.description = func.__doc__
-
         # Set some custom attributes for this command
         setattr(func, constants.SUBCMD_ATTR_COMMAND, command)
         setattr(func, constants.CMD_ATTR_ARGPARSER, parser)