Changed how command not found errors are handled by default: Implemented a cos-likeness algorithm (Coling 2008) for comparing strings, which allows for decent suggestions and speed.

src/commands/cmdhandler.py

@@ -42,6 +42,7 @@ from django.conf import settings
 from src.comms.channelhandler import CHANNELHANDLER
 from src.utils import logger, utils
 from src.commands.cmdparser import at_multimatch_cmd
+from src.utils.utils import string_suggestions
 
 __all__ = ("cmdhandler",)
 
@@ -191,7 +192,12 @@ def cmdhandler(caller, raw_string, testing=False):
                 if syscmd:
                     sysarg = raw_string
                 else:
-                    sysarg = "Huh? (Type \"help\" for help)"
+                    sysarg = "Command '%s' is not available." % raw_string
+                    suggestions = string_suggestions(raw_string, cmdset.get_all_cmd_keys_and_aliases(), cutoff=0.7, maxnum=3)
+                    if suggestions:
+                        sysarg += " Did you maybe mean %s?" % utils.list_to_string(suggestions, 'or', addquote=True)
+                    else:
+                        sysarg += " Type \"help\" for help."
                 raise ExecSystemCommand(syscmd, sysarg)
 
             if len(matches) > 1:

src/commands/cmdset.py

@@ -382,3 +382,12 @@ class CmdSet(object):
         by use of self.add().
         """
         pass
+
+    def get_all_cmd_keys_and_aliases(self):
+        """
+        Returns a list of all command keys and aliases
+        available in this cmdset.
+        """
+        names = [cmd.key for cmd in self.commands]
+        [names.extend(cmd.aliases) for cmd in self.commands]
+        return names

src/commands/default/help.py

@@ -6,6 +6,7 @@ set. The normal, database-tied help system is used for collaborative
 creation of other help topics such as RP help or game-world aides.
 """
 
+from collections import defaultdict
 from src.utils.utils import fill, dedent
 from src.commands.command import Command
 from src.help.models import HelpEntry
@@ -100,20 +101,14 @@ class CmdHelp(Command):
 
         if query in LIST_ARGS:
             # we want to list all available help entries, grouped by category.
-            hdict_cmd = {}
+            hdict_cmd = defaultdict(list)
             for cmd in (cmd for cmd in cmdset if cmd.auto_help and not cmd.is_exit
                         and not cmd.key.startswith('__') and cmd.access(caller)):
-                try:
-                    hdict_cmd[cmd.help_category].append(cmd.key)
-                except KeyError:
-                    hdict_cmd[cmd.help_category] = [cmd.key]
-            hdict_db = {}
+                hdict_cmd[cmd.help_category].append(cmd.key)
+            hdict_db = defaultdict(list)
             for topic in (topic for topic in HelpEntry.objects.get_all_topics()
                           if topic.access(caller, 'view', default=True)):
-                try:
-                    hdict_db[topic.help_category].append(topic.key)
-                except KeyError:
-                    hdict_db[topic.help_category] = [topic.key]
+                hdict_db[topic.help_category].append(topic.key)
             help_entry = format_help_list(hdict_cmd, hdict_db)
             caller.msg(help_entry)
             return