""" CmdSethandler The Cmdsethandler tracks an object's 'Current CmdSet', which is the current merged sum of all CmdSets added to it. A CmdSet constitues a set of commands. The CmdSet works as a special intelligent container that, when added to other CmdSet make sure that same-name commands are treated correctly (usually so there are no doublets). This temporary but up-to-date merger of CmdSet is jointly called the Current Cmset. It is this Current CmdSet that the commandhandler looks through whenever a player enters a command (it also adds CmdSets from objects in the room in real-time). All player objects have a 'default cmdset' containing all the normal in-game mud commands (look etc). So what is all this cmdset complexity good for? In its simplest form, a CmdSet has no commands, only a key name. In this case the cmdset's use is up to each individual game - it can be used by an AI module for example (mobs in cmdset 'roam' move from room to room, in cmdset 'attack' they enter combat with players). Defining commands in cmdsets offer some further powerful game-design consequences however. Here are some examples: As mentioned above, all players always have at least the Default CmdSet. This contains the set of all normal-use commands in-game, stuff like look and @desc etc. Now assume our players end up in a dark room. You don't want the player to be able to do much in that dark room unless they light a candle. You could handle this by changing all your normal commands to check if the player is in a dark room. This rapidly goes unwieldly and error prone. Instead you just define a cmdset with only those commands you want to be available in the 'dark' cmdset - maybe a modified look command and a 'light candle' command - and have this completely replace the default cmdset. Another example: Say you want your players to be able to go fishing. You could implement this as a 'fish' command that fails whenever the player has no fishing rod. Easy enough. But what if you want to make fishing more complex - maybe you want four-five different commands for throwing your line, reeling in, etc? Most players won't (we assume) have fishing gear, and having all those detailed commands is cluttering up the command list. And what if you want to use the 'throw' command also for throwing rocks etc instead of 'using it up' for a minor thing like fishing? So instead you put all those detailed fishing commands into their own CommandSet called 'Fishing'. Whenever the player gives the command 'fish' (presumably the code checks there is also water nearby), only THEN this CommandSet is added to the Cmdhandler of the player. The 'throw' command (which normally throws rocks) is replaced by the custom 'fishing variant' of throw. What has happened is that the Fishing CommandSet was merged on top of the Default ones, and due to how we defined it, its command overrules the default ones. When we are tired of fishing, we give the 'go home' command (or whatever) and the Cmdhandler simply removes the fishing CommandSet so that we are back at defaults (and can throw rocks again). Since any number of CommandSets can be piled on top of each other, you can then implement separate sets for different situations. For example, you can have a 'On a boat' set, onto which you then tack on the 'Fishing' set. Fishing from a boat? No problem! """ from src.utils import logger, utils from src.commands.cmdset import CmdSet from src.server.models import ServerConfig from django.utils.translation import ugettext as _ __all__ = ("import_cmdset", "CmdSetHandler") _CACHED_CMDSETS = {} class _ErrorCmdSet(CmdSet): "This is a special cmdset used to report errors" key = "_CMDSET_ERROR" errmessage = "Error when loading cmdset." def import_cmdset(python_path, cmdsetobj, emit_to_obj=None, no_logging=False): """ This helper function is used by the cmdsethandler to load a cmdset instance from a python module, given a python_path. It's usually accessed through the cmdsethandler's add() and add_default() methods. python_path - This is the full path to the cmdset object. cmdsetobj - the database object/typeclass on which this cmdset is to be assigned (this can be also channels and exits, as well as players but there will always be such an object) emit_to_obj - if given, error is emitted to this object (in addition to logging) no_logging - don't log/send error messages. This can be useful if import_cmdset is just used to check if this is a valid python path or not. function returns None if an error was encountered or path not found. """ try: try: #print "importing %s: _CACHED_CMDSETS=%s" % (python_path, _CACHED_CMDSETS) wanted_cache_key = python_path cmdsetclass = _CACHED_CMDSETS.get(wanted_cache_key, None) errstring = "" if not cmdsetclass: #print "cmdset '%s' not in cache. Reloading %s on %s." % (wanted_cache_key, python_path, cmdsetobj) # Not in cache. Reload from disk. modulepath, classname = python_path.rsplit('.', 1) module = __import__(modulepath, fromlist=[True]) cmdsetclass = module.__dict__[classname] _CACHED_CMDSETS[wanted_cache_key] = cmdsetclass #instantiate the cmdset (and catch its errors) if callable(cmdsetclass): cmdsetclass = cmdsetclass(cmdsetobj) return cmdsetclass except ImportError: errstring = _("Error loading cmdset: Couldn't import module '%s'.") errstring = errstring % modulepath raise except KeyError: errstring = _("Error in loading cmdset: No cmdset class '%(classname)s' in %(modulepath)s.") errstring = errstring % {"classname": classname, "modulepath": modulepath} raise except Exception: errstring = _("Compile/Run error when loading cmdset '%s'. Error was logged.") errstring = errstring % (python_path) raise except Exception: # returning an empty error cmdset if not no_logging: logger.log_trace(errstring) if emit_to_obj and not ServerConfig.objects.conf("server_starting_mode"): object.__getattribute__(emit_to_obj, "msg")(errstring) err_cmdset = _ErrorCmdSet() err_cmdset.errmessage = errstring return err_cmdset # classes class CmdSetHandler(object): """ The CmdSetHandler is always stored on an object, this object is supplied as an argument. The 'current' cmdset is the merged set currently active for this object. This is the set the game engine will retrieve when determining which commands are available to the object. The cmdset_stack holds a history of all CmdSets to allow the handler to remove/add cmdsets at will. Doing so will re-calculate the 'current' cmdset. """ def __init__(self, obj): """ This method is called whenever an object is recreated. obj - this is a reference to the game object this handler belongs to. """ self.obj = obj # the id of the "merged" current cmdset for easy access. self.key = None # this holds the "merged" current command set self.current = None # this holds a history of CommandSets self.cmdset_stack = [CmdSet(cmdsetobj=self.obj, key="Empty")] # this tracks which mergetypes are actually in play in the stack self.mergetype_stack = ["Union"] # the subset of the cmdset_paths that are to be stored in the database self.permanent_paths = [""] #self.update(init_mode=True) is then called from the object __init__. def __str__(self): "Display current commands" string = "" mergelist = [] if len(self.cmdset_stack) > 1: # We have more than one cmdset in stack; list them all #print self.cmdset_stack, self.mergetype_stack for snum, cmdset in enumerate(self.cmdset_stack): mergetype = self.mergetype_stack[snum] permstring = "non-perm" if cmdset.permanent: permstring = "perm" if mergetype != cmdset.mergetype: mergetype = "%s^" % (mergetype) string += "\n %i: <%s (%s, prio %i, %s)>: %s" % \ (snum, cmdset.key, mergetype, cmdset.priority, permstring, cmdset) mergelist.append(str(snum)) string += "\n" # Display the currently active cmdset, limited by self.obj's permissions mergetype = self.mergetype_stack[-1] if mergetype != self.current.mergetype: merged_on = self.cmdset_stack[-2].key mergetype = _("custom %(mergetype)s on cmdset '%(merged_on)s'") % \ {"mergetype": mergetype, "merged_on":merged_on} if mergelist: string += _(" : %(current)s") % \ {"mergelist": "+".join(mergelist), "mergetype": mergetype, "prio": self.current.priority, "current":self.current} else: permstring = "non-perm" if self.current.permanent: permstring = "perm" string += _(" <%(key)s (%(mergetype)s, prio %(prio)i, %(permstring)s)>: %(keylist)s") % \ {"key": self.current.key, "mergetype": mergetype, "prio": self.current.priority, "permstring": permstring, "keylist": ", ".join(cmd.key for cmd in sorted(self.current, key=lambda o: o.key))} return string.strip() def _import_cmdset(self, cmdset_path, emit_to_obj=None): """ Method wrapper for import_cmdset. load a cmdset from a module. cmdset_path - the python path to an cmdset object. emit_to_obj - object to send error messages to """ if not emit_to_obj: emit_to_obj = self.obj return import_cmdset(cmdset_path, self.obj, emit_to_obj) def update(self, init_mode=False): """ Re-adds all sets in the handler to have an updated current set. init_mode is used right after this handler was created; it imports all permanent cmdsets from db. """ if init_mode: # reimport all permanent cmdsets storage = self.obj.cmdset_storage #print "cmdset_storage:", self.obj.cmdset_storage if storage: self.cmdset_stack = [] for pos, path in enumerate(storage): if pos == 0 and not path: self.cmdset_stack = [CmdSet(cmdsetobj=self.obj, key="Empty")] elif path: cmdset = self._import_cmdset(path) if cmdset: cmdset.permanent = cmdset.key != '_ERROR_CMDSET' self.cmdset_stack.append(cmdset) # merge the stack into a new merged cmdset new_current = None self.mergetype_stack = [] for cmdset in self.cmdset_stack: try: # for cmdset's '+' operator, order matters. new_current = cmdset + new_current except TypeError: continue self.mergetype_stack.append(new_current.actual_mergetype) self.current = new_current def add(self, cmdset, emit_to_obj=None, permanent=False): """ Add a cmdset to the handler, on top of the old ones. Default is to not make this permanent, i.e. the set will not survive a server reset. cmdset - can be a cmdset object or the python path to such an object. emit_to_obj - an object to receive error messages. permanent - this cmdset will remain across a server reboot Note: An interesting feature of this method is if you were to send it an *already instantiated cmdset* (i.e. not a class), the current cmdsethandler's obj attribute will then *not* be transferred over to this already instantiated set (this is because it might be used elsewhere and can cause strange effects). This means you could in principle have the handler launch command sets tied to a *different* object than the handler. Not sure when this would be useful, but it's a 'quirk' that has to be documented. """ if callable(cmdset): if not utils.inherits_from(cmdset, CmdSet): raise Exception(_("Only CmdSets can be added to the cmdsethandler!")) cmdset = cmdset(self.obj) elif isinstance(cmdset, basestring): # this is (maybe) a python path. Try to import from cache. cmdset = self._import_cmdset(cmdset) if cmdset and cmdset.key != '_CMDSET_ERROR': if permanent and cmdset.key != '_CMDSET_ERROR': # store the path permanently cmdset.permanent = True storage = self.obj.cmdset_storage if not storage: storage = ["", cmdset.path] else: storage.append(cmdset.path) self.obj.cmdset_storage = storage else: cmdset.permanent = False self.cmdset_stack.append(cmdset) self.update() def add_default(self, cmdset, emit_to_obj=None, permanent=True): """ Add a new default cmdset. If an old default existed, it is replaced. If permanent is set, the set will survive a reboot. cmdset - can be a cmdset object or the python path to an instance of such an object. emit_to_obj - an object to receive error messages. permanent - save cmdset across reboots See also the notes for self.add(), which applies here too. """ if callable(cmdset): if not utils.inherits_from(cmdset, CmdSet): raise Exception(_("Only CmdSets can be added to the cmdsethandler!")) cmdset = cmdset(self.obj) elif isinstance(cmdset, basestring): # this is (maybe) a python path. Try to import from cache. cmdset = self._import_cmdset(cmdset) if cmdset and cmdset.key != '_CMDSET_ERROR': if self.cmdset_stack: self.cmdset_stack[0] = cmdset self.mergetype_stack[0] = cmdset.mergetype else: self.cmdset_stack = [cmdset] self.mergetype_stack = [cmdset.mergetype] if permanent and cmdset.key != '_CMDSET_ERROR': cmdset.permanent = True storage = self.obj.cmdset_storage if storage: storage[0] = cmdset.path else: storage = [cmdset.path] self.obj.cmdset_storage = storage else: cmdset.permanent = False self.update() def delete(self, cmdset=None): """ Remove a cmdset from the handler. cmdset can be supplied either as a cmdset-key, an instance of the CmdSet or a python path to the cmdset. If no key is given, the last cmdset in the stack is removed. Whenever the cmdset_stack changes, the cmdset is updated. The default cmdset (first entry in stack) is never removed - remove it explicitly with delete_default. """ if len(self.cmdset_stack) < 2: # don't allow deleting default cmdsets here. return if not cmdset: # remove the last one in the stack cmdset = self.cmdset_stack.pop() if cmdset.permanent: storage = self.obj.cmdset_storage storage.pop() self.obj.cmdset_storage = storage else: # try it as a callable if callable(cmdset) and hasattr(cmdset, 'path'): delcmdsets = [cset for cset in self.cmdset_stack[1:] if cset.path == cmdset.path] else: # try it as a path or key delcmdsets = [cset for cset in self.cmdset_stack[1:] if cset.path == cmdset or cset.key == cmdset] storage = [] if any(cset.permanent for cset in delcmdsets): # only hit database if there's need to storage = self.obj.cmdset_storage for cset in delcmdsets: if cset.permanent: try: storage.remove(cset.path) except ValueError: pass for cset in delcmdsets: # clean the in-memory stack try: self.cmdset_stack.remove(cset) except ValueError: pass # re-sync the cmdsethandler. self.update() def delete_default(self): """ This explicitly deletes the default cmdset. It's the only command that can. """ if self.cmdset_stack: cmdset = self.cmdset_stack[0] if cmdset.permanent: storage = self.obj.cmdset_storage if storage: storage[0] = "" else: storage = [""] self.cmdset_storage = storage self.cmdset_stack[0] = CmdSet(cmdsetobj=self.obj, key="Empty") else: self.cmdset_stack = [CmdSet(cmdsetobj=self.obj, key="Empty")] self.update() def all(self): """ Returns the list of cmdsets. Mostly useful to check if stack if empty or not. """ return self.cmdset_stack def clear(self): """ Removes all extra Command sets from the handler, leaving only the default one. """ self.cmdset_stack = [self.cmdset_stack[0]] self.mergetype_stack = [self.cmdset_stack[0].mergetype] storage = self.obj.cmdset_storage if storage: storage = storage[0] self.obj.cmdset_storage = storage self.update() def has_cmdset(self, cmdset_key, must_be_default=False): """ checks so the cmdsethandler contains a cmdset with the given key. must_be_default - only match against the default cmdset. """ if must_be_default: return self.cmdset_stack and self.cmdset_stack[0].key == cmdset_key else: return any([cmdset.key == cmdset_key for cmdset in self.cmdset_stack]) def reset(self): """ Force reload of all cmdsets in handler. This should be called after _CACHED_CMDSETS have been cleared (normally by @reload). """ new_cmdset_stack = [] new_mergetype_stack = [] for cmdset in self.cmdset_stack: if cmdset.key == "Empty": new_cmdset_stack.append(cmdset) new_mergetype_stack.append("Union") else: new_cmdset_stack.append(self._import_cmdset(cmdset.path)) new_mergetype_stack.append(cmdset.mergetype) self.cmdset_stack = new_cmdset_stack self.mergetype_stack = new_mergetype_stack self.update()