Merge pull request #643 from python-cmd2/disable_command

Disable commands

Author: kmvanbrunt

CHANGELOG.md

@@ -13,6 +13,14 @@
     * Added ``matches_sort_key`` to override the default way tab completion matches are sorted
     * Added ``StdSim.pause_storage`` member which when True will cause ``StdSim`` to not save the output sent to it.
       See documentation for ``CommandResult`` in ``pyscript_bridge.py`` for reasons pausing the storage can be useful.
+    * Added ability to disable/enable individual commands and entire categories of commands. When a command
+      is disabled, it will not show up in the help menu or tab complete. If a user tries to run the command
+      or call help on it, a command-specific message supplied by the developer will be printed. The following
+      commands were added to support this feature.
+        * ``enable_command()``
+        * ``enable_category()``
+        * ``disable_command()``
+        * ``disable_category()``
 * Potentially breaking changes
     * Made ``cmd2_app`` a positional and required argument of ``AutoCompleter`` since certain functionality now
     requires that it can't be ``None``.

cmd2/cmd2.py

@@ -37,6 +37,7 @@
 import re
 import sys
 import threading
+from collections import namedtuple
 from typing import Any, Callable, Dict, List, Mapping, Optional, Tuple, Type, Union, IO
 
 import colorama
@@ -279,6 +280,10 @@ class EmptyStatement(Exception):
     pass
 
 
+# Contains data about a disabled command which is used to restore its original functions when the command is enabled
+DisabledCommand = namedtuple('DisabledCommand', ['command_function', 'help_function'])
+
+
 class Cmd(cmd.Cmd):
     """An easy but powerful framework for writing line-oriented command interpreters.
 
@@ -521,6 +526,11 @@ def __init__(self, completekey: str = 'tab', stdin=None, stdout=None, persistent
         # being printed by a command.
         self.terminal_lock = threading.RLock()
 
+        # Commands that have been disabled from use. This is to support commands that are only available
+        # during specific states of the application. This dictionary's keys are the command names and its
+        # values are DisabledCommand objects.
+        self.disabled_commands = dict()
+
     # -----  Methods related to presenting output to the user -----
 
     @property
@@ -1562,14 +1572,19 @@ def get_all_commands(self) -> List[str]:
                 if name.startswith(COMMAND_FUNC_PREFIX) and callable(getattr(self, name))]
 
     def get_visible_commands(self) -> List[str]:
-        """Returns a list of commands that have not been hidden."""
+        """Returns a list of commands that have not been hidden or disabled."""
         commands = self.get_all_commands()
 
         # Remove the hidden commands
         for name in self.hidden_commands:
             if name in commands:
                 commands.remove(name)
 
+        # Remove the disabled commands
+        for name in self.disabled_commands:
+            if name in commands:
+                commands.remove(name)
+
         return commands
 
     def get_alias_names(self) -> List[str]:
@@ -1953,7 +1968,7 @@ def cmd_func_name(self, command: str) -> str:
     def onecmd(self, statement: Union[Statement, str]) -> bool:
         """ This executes the actual do_* method for a command.
 
-        If the command provided doesn't exist, then it executes _default() instead.
+        If the command provided doesn't exist, then it executes default() instead.
 
         :param statement: intended to be a Statement instance parsed command from the input stream, alternative
                           acceptance of a str is present only for backward compatibility with cmd
@@ -1969,8 +1984,9 @@ def onecmd(self, statement: Union[Statement, str]) -> bool:
         else:
             func = self.cmd_func(statement.command)
             if func:
-                # Since we have a valid command store it in the history
-                if statement.command not in self.exclude_from_history:
+                # Check to see if this command should be stored in history
+                if statement.command not in self.exclude_from_history \
+                        and statement.command not in self.disabled_commands:
                     self.history.append(statement)
 
                 stop = func(statement)
@@ -3186,13 +3202,15 @@ def do_history(self, args: argparse.Namespace) -> None:
 
         # -v must be used alone with no other options
         if args.verbose:
-            if args.clear or args.edit or args.output_file or args.run or args.transcript or args.expanded or args.script:
+            if args.clear or args.edit or args.output_file or args.run or args.transcript \
+                    or args.expanded or args.script:
                 self.poutput("-v can not be used with any other options")
                 self.poutput(self.history_parser.format_usage())
                 return
 
         # -s and -x can only be used if none of these options are present: [-c -r -e -o -t]
-        if (args.script or args.expanded) and (args.clear or args.edit or args.output_file or args.run or args.transcript):
+        if (args.script or args.expanded) \
+                and (args.clear or args.edit or args.output_file or args.run or args.transcript):
             self.poutput("-s and -x can not be used with -c, -r, -e, -o, or -t")
             self.poutput(self.history_parser.format_usage())
             return
@@ -3598,6 +3616,95 @@ def set_window_title(self, title: str) -> None:  # pragma: no cover
         else:
             raise RuntimeError("another thread holds terminal_lock")
 
+    def enable_command(self, command: str) -> None:
+        """
+        Enable a command by restoring its functions
+        :param command: the command being enabled
+        """
+        # If the commands is already enabled, then return
+        if command not in self.disabled_commands:
+            return
+
+        help_func_name = HELP_FUNC_PREFIX + command
+
+        # Restore the command and help functions to their original values
+        dc = self.disabled_commands[command]
+        setattr(self, self.cmd_func_name(command), dc.command_function)
+
+        if dc.help_function is None:
+            delattr(self, help_func_name)
+        else:
+            setattr(self, help_func_name, dc.help_function)
+
+        # Remove the disabled command entry
+        del self.disabled_commands[command]
+
+    def enable_category(self, category: str) -> None:
+        """
+        Enable an entire category of commands
+        :param category: the category to enable
+        """
+        for cmd_name in list(self.disabled_commands):
+            dc = self.disabled_commands[cmd_name]
+            cmd_category = getattr(dc.command_function, HELP_CATEGORY, None)
+            if cmd_category is not None and cmd_category == category:
+                self.enable_command(cmd_name)
+
+    def disable_command(self, command: str, message_to_print: str) -> None:
+        """
+        Disable a command and overwrite its functions
+        :param command: the command being disabled
+        :param message_to_print: what to print when this command is run or help is called on it while disabled
+        """
+        import functools
+
+        # If the commands is already disabled, then return
+        if command in self.disabled_commands:
+            return
+
+        # Make sure this is an actual command
+        command_function = self.cmd_func(command)
+        if command_function is None:
+            raise AttributeError("{} does not refer to a command".format(command))
+
+        help_func_name = HELP_FUNC_PREFIX + command
+
+        # Add the disabled command record
+        self.disabled_commands[command] = DisabledCommand(command_function=command_function,
+                                                          help_function=getattr(self, help_func_name, None))
+
+        # Overwrite the command and help functions to print the message
+        new_func = functools.partial(self._report_disabled_command_usage, message_to_print=message_to_print)
+        setattr(self, self.cmd_func_name(command), new_func)
+        setattr(self, help_func_name, new_func)
+
+    def disable_category(self, category: str, message_to_print: str) -> None:
+        """
+        Disable an entire category of commands
+        :param category: the category to disable
+        :param message_to_print: what to print when anything in this category is run or help is called on it
+                                 while disabled
+        """
+        all_commands = self.get_all_commands()
+
+        for cmd_name in all_commands:
+            func = self.cmd_func(cmd_name)
+            cmd_category = getattr(func, HELP_CATEGORY, None)
+
+            # If this command is in the category, then disable it
+            if cmd_category is not None and cmd_category == category:
+                self.disable_command(cmd_name, message_to_print)
+
+    # noinspection PyUnusedLocal
+    def _report_disabled_command_usage(self, *args, message_to_print: str, **kwargs) -> None:
+        """
+        Report when a disabled command has been run or had help called on it
+        :param args: not used
+        :param message_to_print: the message reporting that the command is disabled
+        :param kwargs: not used
+        """
+        self.poutput(message_to_print)
+
     def cmdloop(self, intro: Optional[str] = None) -> None:
         """This is an outer wrapper around _cmdloop() which deals with extra features provided by cmd2.
 

docs/argument_processing.rst

@@ -195,138 +195,6 @@ Which yields:
 .. _argparse: https://docs.python.org/3/library/argparse.html
 
 
-Grouping Commands
-=================
-
-By default, the ``help`` command displays::
-
-  Documented commands (type help <topic>):
-  ========================================
-  alias    findleakers  pyscript    sessions             status       vminfo
-  config   help         quit        set                  stop         which
-  connect  history      redeploy    shell                thread_dump
-  deploy   list         resources   shortcuts            unalias
-  edit     load         restart     sslconnectorciphers  undeploy
-  expire   py           serverinfo  start                version
-
-If you have a large number of commands, you can optionally group your commands into categories.
-Here's the output from the example ``help_categories.py``::
-
-  Documented commands (type help <topic>):
-
-  Application Management
-  ======================
-  deploy  findleakers  redeploy  sessions  stop
-  expire  list         restart   start     undeploy
-
-  Connecting
-  ==========
-  connect  which
-
-  Server Information
-  ==================
-  resources  serverinfo  sslconnectorciphers  status  thread_dump  vminfo
-
-  Other
-  =====
-  alias   edit  history  py        quit  shell      unalias
-  config  help  load     pyscript  set   shortcuts  version
-
-
-There are 2 methods of specifying command categories, using the ``@with_category`` decorator or with the
-``categorize()`` function. Once a single command category is detected, the help output switches to a categorized
-mode of display. All commands with an explicit category defined default to the category `Other`.
-
-Using the ``@with_category`` decorator::
-
-  @with_category(CMD_CAT_CONNECTING)
-  def do_which(self, _):
-      """Which command"""
-      self.poutput('Which')
-
-Using the ``categorize()`` function:
-
-    You can call with a single function::
-
-        def do_connect(self, _):
-            """Connect command"""
-            self.poutput('Connect')
-
-        # Tag the above command functions under the category Connecting
-        categorize(do_connect, CMD_CAT_CONNECTING)
-
-    Or with an Iterable container of functions::
-
-        def do_undeploy(self, _):
-            """Undeploy command"""
-            self.poutput('Undeploy')
-
-        def do_stop(self, _):
-            """Stop command"""
-            self.poutput('Stop')
-
-        def do_findleakers(self, _):
-            """Find Leakers command"""
-            self.poutput('Find Leakers')
-
-        # Tag the above command functions under the category Application Management
-        categorize((do_undeploy,
-                    do_stop,
-                    do_findleakers), CMD_CAT_APP_MGMT)
-
-The ``help`` command also has a verbose option (``help -v`` or ``help --verbose``) that combines
-the help categories with per-command Help Messages::
-
-    Documented commands (type help <topic>):
-
-    Application Management
-    ================================================================================
-    deploy              Deploy command
-    expire              Expire command
-    findleakers         Find Leakers command
-    list                List command
-    redeploy            Redeploy command
-    restart             usage: restart [-h] {now,later,sometime,whenever}
-    sessions            Sessions command
-    start               Start command
-    stop                Stop command
-    undeploy            Undeploy command
-
-    Connecting
-    ================================================================================
-    connect             Connect command
-    which               Which command
-
-    Server Information
-    ================================================================================
-    resources              Resources command
-    serverinfo             Server Info command
-    sslconnectorciphers    SSL Connector Ciphers command is an example of a command that contains
-                           multiple lines of help information for the user. Each line of help in a
-                           contiguous set of lines will be printed and aligned in the verbose output
-                           provided with 'help --verbose'
-    status                 Status command
-    thread_dump            Thread Dump command
-    vminfo                 VM Info command
-
-    Other
-    ================================================================================
-    alias               Define or display aliases
-    config              Config command
-    edit                Edit a file in a text editor
-    help                List available commands with "help" or detailed help with "help cmd"
-    history             usage: history [-h] [-r | -e | -s | -o FILE | -t TRANSCRIPT] [arg]
-    load                Runs commands in script file that is encoded as either ASCII or UTF-8 text
-    py                  Invoke python command, shell, or script
-    pyscript            Runs a python script file inside the console
-    quit                Exits this application
-    set                 usage: set [-h] [-a] [-l] [settable [settable ...]]
-    shell               Execute a command as if at the OS prompt
-    shortcuts           Lists shortcuts available
-    unalias             Unsets aliases
-    version             Version command
-
-
 Receiving an argument list
 ==========================