Channels

In a multiplayer game, players often need other means of in-game communication than moving to the same room and use say or emote.

Channels allows Evennia’s to act as a fancy chat program. When a player is connected to a channel, sending a message to it will automatically distribute it to every other subscriber.

Channels can be used both for chats between Accounts and between Objects (usually Characters). Chats could be both OOC (out-of-character) or IC (in-charcter) in nature. Some examples:

  • A support channel for contacting staff (OOC)

  • A general chat for discussing anything and foster community (OOC)

  • Admin channel for private staff discussions (OOC)

  • Private guild channels for planning and organization (IC/OOC depending on game)

  • Cyberpunk-style retro chat rooms (IC)

  • In-game radio channels (IC)

  • Group telephathy (IC)

  • Walkie talkies (IC)

Changed in version 1.0: Channel system changed to use a central ‘channel’ command and nicks instead of auto-generated channel-commands and -cmdset. ChannelHandler was removed.

Working with channels

Viewing and joining channels

In the default command set, channels are all handled via the mighty channel command, channel (or chan). By default, this command will assume all entities dealing with channels are Accounts.

Viewing channels

channel       - shows your subscriptions
channel/all   - shows all subs available to you
channel/who   - shows who subscribes to this channel

To join/unsub a channel do

channel/sub channelname
channel/unsub channelname

If you temporarily don’t want to hear the channel for a while (without actually unsubscribing), you can mute it:

channel/mute channelname
channel/unmute channelname

Talk on channels

To speak on a channel, do

channel public Hello world!

If the channel-name has spaces in it, you need to use a ‘=’:

channel rest room = Hello world!

Now, this is more to type than we’d like, so when you join a channel, the system automatically sets up an personal alias so you can do this instead:

public Hello world

Warning

This shortcut will not work if the channel-name has spaces in it. So channels with long names should make sure to provide a one-word alias as well.

Any user can make up their own channel aliases:

channel/alias public = foo;bar

You can now just do

foo Hello world!
bar Hello again!

And even remove the default one if they don’t want to use it

channel/unalias public
public Hello    (gives a command-not-found error now)

But you can also use your alias with the channel command:

channel foo Hello world!

What happens when aliasing is that a nick is created that maps your alias + argument onto calling the channel command. So when you enter foo hello, what the server sees is actually channel foo = hello. The system is also clever enough to know that whenever you search for channels, your channel-nicks should also be considered so as to convert your input to an existing channel name.

You can check if you missed channel conversations by viewing the channel’s scrollback with

channel/history public

This retrieves the last 20 lines of text (also from a time when you were offline). You can step further back by specifying how many lines back to start:

channel/history public = 30

This again retrieve 20 lines, but starting 30 lines back (so you’ll get lines 30-50 counting backwards).

Channel administration

Evennia can create certain channels when it starts. Channels can also be created on-the-fly in-game.

Default channels from settings

You can specify ‘default’ channels you want to auto-create from the Evennia settings. New accounts will automatically be subscribed to such ‘default’ channels if they have the right permissions. This is a list of one dict per channel (example is the default public channel):

# in mygame/server/conf/settings.py
DEFAULT_CHANNELS = [ 
	{
         "key": "Public",
         "aliases": ("pub",),
         "desc": "Public discussion",
         "locks": "control:perm(Admin);listen:all();send:all()",
     },
]

Each dict is fed as **channeldict into the create_channel function, and thus supports all the same keywords.

Evennia also has two system-related channels:

  • CHANNEL_MUDINFO is a dict describing the “MudInfo” channel. This is assumed to exist and is a place for Evennia to echo important server information. The idea is that server admins and staff can subscribe to this channel to stay in the loop.

  • CHANNEL_CONECTINFO is not defined by default. It will receive connect/disconnect-messages and could be visible also for regular players. If not given, connection-info will just be logged quietly.

Managing channels in-game

To create/destroy a new channel on the fly you can do

channel/create channelname;alias;alias = description
channel/destroy channelname

Aliases are optional but can be good for obvious shortcuts everyone may want to use. The description is used in channel-listings. You will automatically join a channel you created and will be controlling it. You can also use channel/desc to change the description on a channel you wnn later.

If you control a channel you can also kick people off it:

channel/boot mychannel = annoyinguser123 : stop spamming!

The last part is an optional reason to send to the user before they are booted. You can give a comma-separated list of channels to kick the same user from all those channels at once. The user will be unsubbed from the channel and all their aliases will be wiped. But they can still rejoin if they like.

channel/ban mychannel = annoyinguser123
channel/ban      - view bans
channel/unban mychannel = annoyinguser123

Banning adds the user to the channels blacklist. This means they will not be able to rejoin if you boot them. You will need to run channel/boot to actually kick them out.

See the Channel command api docs (and in-game help) for more details.

Admin-level users can also modify channel’s locks:

channel/lock buildchannel = listen:all();send:perm(Builders)

Channels use three lock-types by default:

  • listen - who may listen to the channel. Users without this access will not even be able to join the channel and it will not appear in listings for them.

  • send - who may send to the channel.

  • control - this is assigned to you automatically when you create the channel. With control over the channel you can edit it, boot users and do other management tasks.

Restricting channel administration

By default everyone can use the channel command (evennia.commands.default.comms.CmdChannel) to create channels and will then control the channels they created (to boot/ban people etc). If you as a developer does not want regular players to do this (perhaps you want only staff to be able to spawn new channels), you can override the channel command and change its locks property.

The default help command has the following locks property:

    locks = "cmd:not perm(channel_banned); admin:all(); manage:all(); changelocks: perm(Admin)"

This is a regular lockstring.

  • cmd: pperm(channel_banned) - The cmd locktype is the standard one used for all Commands. an accessing object failing this will not even know that the command exists. The pperm() lockfunc checks an on-account [Permission](Building Permissions) ‘channel_banned’ - and the not means that if they have that ‘permission’ they are cut off from using the channel command. You usually don’t need to change this lock.

  • admin:all() - this is a lock checked in the channel command itself. It controls access to the /boot, /ban and /unban switches (by default letting everyone use them).

  • manage:all() - this controls access to the /create, /destroy, /desc switches.

  • changelocks: perm(Admin) - this controls access to the /lock and /unlock switches. By default this is something only [Admins](Building Permissions) can change.

Note - while admin:all() and manage:all() will let everyone use these switches, users will still only be able to admin or destroy channels they actually control!

If you only want (say) Builders and higher to be able to create and admin channels you could override the help command and change the lockstring to:

  # in for example mygame/commands/commands.py

  from evennia import default_cmds

  class MyCustomChannelCmd(default_cmds.CmdChannel):
      locks = "cmd: not pperm(channel_banned);admin:perm(Builder);manage:perm(Builder);changelocks:perm(Admin)"

Add this custom command to your default cmdset and regular users wil now get an access-denied error when trying to use use these switches.

Using channels in code

For most common changes, the default channel, the recipient hooks and possibly overriding the channel command will get you very far. But you can also tweak channels themselves.

Allowing Characters to use Channels

The default channel command (evennia.commands.default.comms.CmdChannel) sits in the Account command set. It is set up such that it will always operate on Accounts, even if you were to add it to the CharacterCmdSet.

It’s a one-line change to make this command accept non-account callers. But for convenience we provide a version for Characters/Objects. Just import evennia.commands.default.comms.CmdObjectChannel and inherit from that instead.

Customizing channel output and behavior

When distributing a message, the channel will call a series of hooks on itself and (more importantly) on each recipient. So you can customize things a lot by just modifying hooks on your normal Object/Account typeclasses.

Internally, the message is sent with channel.msg(message, senders=sender, bypass_mute=False, **kwargs), where bypass_mute=True means the message ignores muting (good for alerts or if you delete the channel etc) and **kwargs are any extra info you may want to pass to the hooks. The senders (it’s always only one in the default implementation but could in principle be multiple) and bypass_mute are part of the kwargs below:

  1. channel.at_pre_msg(message, **kwargs)

  2. For each recipient:

    • message = recipient.at_pre_channel_msg(message, channel, **kwargs) - allows for the message to be tweaked per-receiver (for example coloring it depending on the users’ preferences). If this method returns False/None, that recipient is skipped.

    • recipient.channel_msg(message, channel, **kwargs) - actually sends to recipient.

    • recipient.at_post_channel_msg(message, channel, **kwargs) - any post-receive effects.

  3. channel.at_post_channel_msg(message, **kwargs)

Note that Accounts and Objects both have their have separate sets of hooks. So make sure you modify the set actually used by your subcribers (or both). Default channels all use Account subscribers.

Channel class

Channels are Typeclassed entities. This means they are persistent in the database, can have attributes and Tags and can be easily extended.

To change which channel typeclass Evennia uses for default commands, change settings.BASE_CHANNEL_TYPECLASS. The base command class is evennia.comms.comms.DefaultChannel. There is an empty child class in mygame/typeclasses/channels.py, same as for other typelass-bases.

In code you create a new channel with evennia.create_channel or Channel.create:

  from evennia import create_channel, search_object
  from typeclasses.channels import Channel

  channel = create_channel("my channel", aliases=["mychan"], locks=..., typeclass=...)
  # alternative
  channel = Channel.create("my channel", aliases=["mychan"], locks=...)

  # connect to it
  me = search_object(key="Foo")[0]
  channel.connect(me)

  # send to it (this will trigger the channel_msg hooks described earlier)
  channel.msg("Hello world!", senders=me)

  # view subscriptions (the SubscriptionHandler handles all subs under the hood)
  channel.subscriptions.has(me)    # check we subbed
  channel.subscriptions.all()      # get all subs
  channel.subscriptions.online()   # get only subs currently online
  channel.subscriptions.clear()    # unsub all

  # leave channel
  channel.disconnect(me)

  # permanently delete channel (will unsub everyone)
  channel.delete()

The Channel’s .connect method will accept both Account and Object subscribers and will handle them transparently.

The channel has many more hooks, both hooks shared with all typeclasses as well as special ones related to muting/banning etc. See the channel class for details.

Channel logging

Changed in version 0.7: Channels changed from using Msg to TmpMsg and optional log files.

Changed in version 1.0: Channels stopped supporting Msg and TmpMsg, using only log files.

The channel messages are not stored in the database. A channel is instead always logged to a regular text log-file mygame/server/logs/channel_<channelname>.log. This is where channels/history channelname gets its data from. A channel’s log will rotate when it grows too big, which thus also automatically limits the max amount of history a user can view with /history.

The log file name is set on the channel class as the log_file property. This is a string that takes the formatting token {channelname} to be replaced with the (lower-case) name of the channel. By default the log is written to in the channel’s at_post_channel_msg method.

Properties on Channels

Channels have all the standard properties of a Typeclassed entity (key, aliases, attributes, tags, locks etc). This is not an exhaustive list; see the Channel api docs for details.

  • send_to_online_only - this class boolean defaults to True and is a sensible optimization since people offline people will not see the message anyway.

  • log_file - this is a string that determines the name of the channel log file. Default is "channel_{channelname}.log". The log file will appear in settings.LOG_DIR (usually mygame/server/logs/). You should usually not change this.

  • channel_prefix_string - this property is a string to easily change how the channel is prefixed. It takes the channelname format key. Default is "[{channelname}] " and produces output like [public] ....

  • subscriptions - this is the SubscriptionHandler, which has methods has, add, remove, all, clear and also online (to get only actually online channel-members).

  • wholist, mutelist, banlist are properties that return a list of subscribers, as well as who are currently muted or banned.

  • channel_msg_nick_pattern - this is a regex pattern for performing the in-place nick replacement (detect that channelalias <msg means that you want to send a message to a channel). This pattern accepts an {alias} formatting marker. Don’t mess with this unless you really want to change how channels work.

  • channel_msg_nick_replacement - this is a string on the [nick replacement

  • form](./Nicks.md). It accepts the {channelname} formatting tag. This is strongly tied to the channel command and is by default channel {channelname} = $1.

Notable Channel hooks:

  • at_pre_channel_msg(message, **kwargs) - called before sending a message, to modify it. Not used by default.

  • msg(message, senders=..., bypass_mute=False, **kwargs) - send the message onto the channel. The **kwargs are passed on into the other call hooks (also on the recipient).

  • at_post_channel_msg(message, **kwargs) - by default this is used to store the message to the log file.

  • channel_prefix(message) - this is called to allow the channel to prefix. This is called by the object/account when they build the message, so if wanting something else one can also just remove that call.

  • every channel message. By default it just returns channel_prefix_string.

  • has_connection(subscriber) - shortcut to check if an entity subscribes to this channel.

  • mute/unmute(subscriber) - this mutes the channel for this user.

  • ban/unban(subscriber) - adds/remove user from banlist.

  • connect/disconnect(subscriber) - adds/removes a subscriber.

  • add_user_channel_alias(user, alias, **kwargs) - sets up a user-nick for this channel. This is what maps e.g. alias <msg> to channel channelname = <msg>.

  • remove_user_channel_alias(user, alias, **kwargs) - remove an alias. Note that this is a class-method that will happily remove found channel-aliases from the user linked to any channel, not only from the channel the method is called on.

  • pre_join_channel(subscriber) - if this returns False, connection will be refused.

  • post_join_channel(subscriber) - by default this sets up a users’s channel-nicks/aliases.

  • pre_leave_channel(subscriber) - if this returns False, the user is not allowed to leave.

  • post_leave_channel(subscriber) - this will clean up any channel aliases/nicks of the user.

  • delete the standard typeclass-delete mechanism will also automatically un-subscribe all subscribers (and thus wipe all their aliases).