wyvern.kernel.commands
Class NullEvent

java.lang.Object
  wyvern.kernel.properties.PList
      wyvern.kernel.commands.EventImpl
          wyvern.kernel.commands.NullEvent

All Implemented Interfaces:

Broadcaster, Command, CommandEvent, PropertyList

public class NullEvent

extends EventImpl

implements Command

A no-op event. These are useful in various odd situations, when you need to put something in an event queue that has no effect. The delay for the event is used by the kernel, so you can force a queue to wait just by setting the delay on the event. The NullEvent can also be used as a token to indicate that another event has expired completely (including its delay).

A NullEvent is its own Command by default, so you can just create one and stick it in a queue without worrying about it. You can also call setHandler() after constructing it to set a new Command to handle the event.

The pre-hooks and post-hooks do get run for a NullEvent, although it seems unlikely that anyone would want to use them.

Version:

1.0, Aug 16, 1999

Author:

Steve Yegge

Field Summary

Fields inherited from class wyvern.kernel.commands.EventImpl

agent_, appendToFile_, argString_, argStringParsed_, argv_, argvParsed_, delay_, failureMessage_, filterObjects_, filters_, handler_, map_, modified_, originalText_, playerOriginated_, redirectFile_, redirecting_, sendToAgent_, successMessage_, verb_, vetoed_, wizParsed_

Fields inherited from class wyvern.kernel.properties.PList

readOnly_

Fields inherited from interface wyvern.lib.PropertyList

PROPERTY_PACKAGE

Constructor Summary

NullEvent()
Constructs a new NullEvent

NullEvent(java.lang.String text, Commandable agent)
Constructs a new NullEvent

Method Summary

CommandEvent	createEvent(CommandEvent initialInfo) Creates a CommandEvent that encapsulates all the state necessary to perform the command.
boolean	execute(CommandEvent event) Executes the specified CommandEvent.
boolean	knowsCommand(java.lang.String command) Returns true if this Command wants to handle the command.

Methods inherited from class wyvern.kernel.commands.EventImpl

broadcast, broadcast, broadcast, broadcast, broadcast, checkVeto, fail, filterMessage, findAllMatches, findByHashcode, findInMap, findNeighbor, findObject, findTarget, getAgent, getArgs, getArgString, getDelay, getFailureMessage, getFilterObjects, getFilters, getHandler, getMap, getOriginalText, getRedirectFile, getSuccessMessage, getVerb, hasArgs, isAppending, isModified, isMonster, isPlayer, isPlayerOriginated, isRedirecting, isSendingToAgent, isVetoed, isWizard, main, message, message, noArgs, parseArgString, parseARGV, parseVerb, profileParsing, redirectMessage, runPostHooks, runPreHooks, searchInv, searchInvAndMapNearby, searchInvAndMapUnder, searchInvByHashcode, searchMapNearby, searchMapUnder, searchMapUnderByHashcode, setAgent, setArgs, setDelay, setFailureMessage, setHandler, setMap, setModified, setOriginalText, setPlayerOriginated, setSuccessMessage, setVerb, setVeto, toString, veto

Methods inherited from class wyvern.kernel.properties.PList

addProperty, addTransientProperty, adjustDoubleProperty, adjustIntProperty, adjustLongProperty, adjustTransientDoubleProperty, adjustTransientIntProperty, adjustTransientLongProperty, countLocalProperties, debugProperties, dismantlePropertyList, getDoubleProperty, getInheritedProperty, getInteger, getIntProperty, getLocalProperties, getLocalProperty, getLongProperty, getParent, getPersistentDoubleProperty, getPersistentIntProperty, getPersistentLocalProperties, getPersistentLongProperty, getPersistentProperty, getProfilingInfo, getProperties, getProperties, getPropertiesIncludingTransients, getPropertiesIncludingTransients, getProperty, getSerializableProperties, getSerializableProperty, getStringProperty, getTransientDoubleProperty, getTransientIntProperty, getTransientLongProperty, getTransientProperties, getTransientProperty, hasLocalProperty, hasPersistentProperty, hasProperty, hasTransientProperty, inheritProperty, isReadOnly, isRemoved, isTransientlyRemoved, printLocalProperties, printProperties, printProperties, printTransientProperties, removeProperty, removeTransientProperty, setDoubleProperty, setIntProperty, setLongProperty, setParent, setProperty, setReadOnly, setTransientDoubleProperty, setTransientIntProperty, setTransientLongProperty, setTransientProperty, toString, transientlyRemoveProperty

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface wyvern.lib.PropertyList

addProperty, addTransientProperty, adjustDoubleProperty, adjustIntProperty, adjustLongProperty, adjustTransientDoubleProperty, adjustTransientIntProperty, adjustTransientLongProperty, countLocalProperties, getDoubleProperty, getInheritedProperty, getIntProperty, getLocalProperties, getLocalProperty, getLongProperty, getParent, getPersistentDoubleProperty, getPersistentIntProperty, getPersistentLocalProperties, getPersistentLongProperty, getPersistentProperty, getProperties, getProperties, getPropertiesIncludingTransients, getPropertiesIncludingTransients, getProperty, getSerializableProperties, getSerializableProperty, getStringProperty, getTransientDoubleProperty, getTransientIntProperty, getTransientLongProperty, getTransientProperties, getTransientProperty, hasLocalProperty, hasPersistentProperty, hasProperty, hasTransientProperty, inheritProperty, isReadOnly, isRemoved, isTransientlyRemoved, printLocalProperties, printProperties, printProperties, printTransientProperties, removeProperty, removeTransientProperty, setDoubleProperty, setIntProperty, setLongProperty, setParent, setProperty, setReadOnly, setTransientDoubleProperty, setTransientIntProperty, setTransientLongProperty, setTransientProperty, toString, transientlyRemoveProperty

Constructor Detail

NullEvent

public NullEvent()

Constructs a new NullEvent

NullEvent

public NullEvent(java.lang.String text,
                 Commandable agent)

Constructs a new NullEvent

Method Detail

createEvent

public CommandEvent createEvent(CommandEvent initialInfo)

Description copied from interface: Command

Creates a CommandEvent that encapsulates all the state necessary to perform the command. A well-designed CommandEvent exposes all of its "properties" so that hook objects can modify its behavior. For instance, many commands result in some sort of message being sent back to the client. The message should be among the properties that hooks can override.

This method is called by the kernel. The kernel passes the event to the pre-hook, then calls Command.execute() (below) to execute the event, and finally calls the post-hook.

Specified by:

createEvent in interface Command

Parameters:

initialInfo - a "blank" CommandEvent containing only the command text and the agent who's performing the command. This initial event is created by the originator of the event (e.g. the AI or player's command preprocessor).

Returns:

a CommandEvent subclass encapsulating this command's execution parameters and state. It should copy in the fields from the passed-in event.

knowsCommand

public boolean knowsCommand(java.lang.String command)

Description copied from interface: Command

Returns true if this Command wants to handle the command. The Command can examine the arguments and determine that it doesn't actually understand the command, in which case it should return false.

This method exists to allow more than one game object to implement the same command verb, but with different expected arguments.

If two objects register for the same command and the same arguments, the object that was registered most recently gets to handle at the command.

Specified by:

knowsCommand in interface Command

Parameters:

command - the entire command string, including arguments

Returns:

true if we want to handle the command

execute

public boolean execute(CommandEvent event)

Description copied from interface: Command

Executes the specified CommandEvent. The CommandEvent contains all the parameters and state required to execute the command; the parameters have been filtered through hook objects, so they may not be the same as when the event was created.

Specified by:

execute in interface Command

Parameters:

event - the CommandEvent to execute

Returns:

true if the event completed successfully, else false.