Refactoring, manhole, ETF support

- s/DiscoClient/Client (was redundant and looked ugly)
- move cached_property to functional utils
- abstract client configuration out to a ClientConfig
- command line utility is now completely isolated from the client
- add ETF (using erlpack) support, optionally enabled via command line
flags (and only works on 2.x because of erlpack)
- Refactor the way gateway events are built a bit
- Add documentation on utilities

README.md

@@ -14,7 +14,8 @@ Disco was built to run both as a generic-use library, and a standalone bot toolk
 |Name|Reason|
 |----|------|
 |requests[security]|adds packages for a proper SSL implementation|
-|rapidjson|provides a Python implementation of the C rapidjson library, improves performance|
+|ujson|faster json parser, improves performance|
+|erlpack|ETF parser, only Python 2.x, run with the --encoder=etf flag|
 
 ## Examples
 

disco/api/client.py

@@ -27,7 +27,7 @@ class APIClient(LoggingClass):
         super(APIClient, self).__init__()
 
         self.client = client
-        self.http = HTTPClient(self.client.token)
+        self.http = HTTPClient(self.client.config.token)
 
     def gateway(self, version, encoding):
         data = self.http(Routes.GATEWAY_GET).json()

disco/bot/bot.py

@@ -1,6 +1,5 @@
 import re
 
-from disco.client import DiscoClient
 from disco.bot.command import CommandEvent
 
 
@@ -13,7 +12,7 @@ class BotConfig(object):
     ----------
     token : str
         The authentication token for this bot. This is passed on to the
-        :class:`disco.client.DiscoClient` without any validation.
+        :class:`disco.client.Client` without any validation.
     commands_enabled : bool
         Whether this bot instance should utilize command parsing. Generally this
         should be true, unless your bot is only handling events and has no user
@@ -61,25 +60,23 @@ class Bot(object):
 
     Parameters
     ----------
-    client : Optional[:class:`disco.client.DiscoClient`]
+    client : :class:`disco.client.Client`
-        The client this bot should utilize for its connection. If not provided,
+        The client this bot should utilize for its connection.
-        will create a new :class:`disco.client.DiscoClient` with the token inside
-        the bot config (:class:`BotConfig`)
     config : Optional[:class:`BotConfig`]
         The configuration to use for this bot. If not provided will use the defaults
         inside of :class:`BotConfig`.
 
     Attributes
     ----------
-    client : `disco.client.DiscoClient`
+    client : `disco.client.Client`
         The client instance for this bot.
     config : `BotConfig`
         The bot configuration instance for this bot.
     plugins : dict(str, :class:`disco.bot.plugin.Plugin`)
         Any plugins this bot has loaded
     """
-    def __init__(self, client=None, config=None):
+    def __init__(self, client, config=None):
-        self.client = client or DiscoClient(config.token)
+        self.client = client
         self.config = config or BotConfig()
 
         self.plugins = {}

disco/bot/command.py

@@ -1,7 +1,7 @@
 import re
 
 from disco.bot.parser import ArgumentSet, ArgumentError
-from disco.util.cache import cached_property
+from disco.util.functional import cached_property
 
 REGEX_FMT = '({})'
 ARGS_REGEX = '( (.*)$|$)'

disco/bot/plugin.py

@@ -92,7 +92,7 @@ class Plugin(LoggingClass, PluginDeco):
 
     Attributes
     ----------
-    client : :class:`disco.client.DiscoClient`
+    client : :class:`disco.client.Client`
         An alias to the client the bot is running with.
     state : :class:`disco.state.State`
         An alias to the state object for the client.

disco/cli.py

@@ -10,10 +10,14 @@ import argparse
 from gevent import monkey
 
 monkey.patch_all()
+
 parser = argparse.ArgumentParser()
 parser.add_argument('--token', help='Bot Authentication Token', required=True)
 parser.add_argument('--shard-count', help='Total number of shards', default=1)
 parser.add_argument('--shard-id', help='Current shard number/id', default=0)
+parser.add_argument('--manhole', action='store_true', help='Enable the manhole', default=False)
+parser.add_argument('--manhole-bind', help='host:port for the manhole to bind too', default='localhost:8484')
+parser.add_argument('--encoder', help='encoder for gateway data', default='json')
 
 logging.basicConfig(level=logging.INFO)
 
@@ -21,23 +25,32 @@ logging.basicConfig(level=logging.INFO)
 def disco_main():
     """
     Creates an argument parser and parses a standard set of command line arguments,
-    creating a new :class:`DiscoClient`.
+    creating a new :class:`Client`.
 
     Returns
     -------
-    :class:`DiscoClient`
+    :class:`Client`
-        A new DiscoClient from the provided command line arguments
+        A new Client from the provided command line arguments
     """
     args = parser.parse_args()
 
+    from disco.client import Client, ClientConfig
+    from disco.gateway.encoding import ENCODERS
     from disco.util.token import is_valid_token
 
     if not is_valid_token(args.token):
         print('Invalid token passed')
         return
 
-    from disco.client import DiscoClient
+    cfg = ClientConfig()
-    return DiscoClient.from_cli(args)
+    cfg.token = args.token
+    cfg.shard_id = args.shard_id
+    cfg.shard_count = args.shard_count
+    cfg.manhole_enable = args.manhole
+    cfg.manhole_bind = args.manhole_bind
+    cfg.encoding_cls = ENCODERS[args.encoder]
+
+    return Client(cfg)
 
 if __name__ == '__main__':
     disco_main().run_forever()

disco/client.py

@@ -1,71 +1,96 @@
-import logging
 import gevent
 
+from gevent.backdoor import BackdoorServer
 from holster.emitter import Emitter
 
 from disco.state import State
 from disco.api.client import APIClient
 from disco.gateway.client import GatewayClient
+from disco.util.logging import LoggingClass
 
-log = logging.getLogger(__name__)
 
+class ClientConfig(LoggingClass):
+    """
+    Configuration for the :class:`Client`.
 
-class DiscoClient(object):
+    Attributes
+    ----------
+    token : str
+        Discord authentication token, ca be validated using the
+        :func:`disco.util.token.is_valid_token` function.
+    shard_id : int
+        The shard ID for the current client instance.
+    shard_count : int
+        The total count of shards running.
+    manhole_enable : bool
+        Whether to enable the manhole (e.g. console backdoor server) utility.
+    manhole_bind : tuple(str, int)
+        A (host, port) combination which the manhole server will bind to (if its
+        enabled using :attr:`manhole_enable`).
+    encoding_cls : class
+        The class to use for encoding/decoding data from websockets.
     """
-    The DiscoClient represents the base entry point to utilizing the Discord API
+
-    through disco. It wraps the functionality of both the REST API, and the realtime
+    token = ""
-    secure websocket gateway.
+    shard_id = 0
+    shard_count = 1
+
+    manhole_enable = True
+    manhole_bind = ('127.0.0.1', 8484)
+
+    encoding_cls = None
+
+
+class Client(object):
+    """
+    Class representing the base entry point that should be used in almost all
+    implementation cases. This class wraps the functionality of both the REST API
+    (:class:`disco.api.client.APIClient`) and the realtime gateway API
+    (:class:`disco.gateway.client.GatewayClient`).
 
     Parameters
     ----------
-    token : str
+    config : :class:`ClientConfig`
-        The Discord authentication token which is used for both the :class:`APIClient`
+        Configuration for this client instance.
-        and the :class:`GatewayClient`. This token can be validated before being
-        passed in, by using the :func:`disco.util.token.is_valid_token` function.
-    sharding : Optional[dict(str, int)]
-        A dictionary containing two pairs with information that is used to control
-        the sharding behavior of the :class:`GatewayClient`. By setting the `number`
-        key, the current shard ID can be controlled. While when setting the `total`
-        key, the total number of running shards can be set.
 
     Attributes
     ----------
+    config : :class:`ClientConfig`
+        The runtime configuration for this client.
     events : :class:`Emitter`
-        An emitter which emits Gateway events
+        An emitter which emits Gateway events.
     packets : :class:`Emitter`
-        An emitter which emits Gateway packets
+        An emitter which emits Gateway packets.
     state : :class:`State`
-        The state tracking object
+        The state tracking object.
     api : :class:`APIClient`
-        The API client
+        The API client.
     gw : :class:`GatewayClient`
-        The gateway client
+        The gateway client.
+    manhole : Optional[:class:`BackdoorServer`]
+        Gevent backdoor server (if the manhole is enabled).
     """
-    def __init__(self, token, sharding=None):
+    def __init__(self, config):
-        self.log = log
+        super(Client, self).__init__()
-        self.token = token
+        self.config = config
-        self.sharding = sharding or {'number': 0, 'total': 1}
 
         self.events = Emitter(gevent.spawn)
         self.packets = Emitter(gevent.spawn)
 
         self.state = State(self)
         self.api = APIClient(self)
-        self.gw = GatewayClient(self)
+        self.gw = GatewayClient(self, self.config.encoding_cls)
 
-    @classmethod
+        if self.config.manhole_enable:
-    def from_cli(cls, args):
+            self.manhole = BackdoorServer(self.config.manhole_bind,
-        """
+                banner='Disco Manhole',
-        Create a new client from a argparse command line argument object, usually
+                locals={
-        generated from the :func:`disco_main` function.
+                    'client': self,
-        """
+                    'state': self.state,
-        inst = cls(
+                    'api': self.api,
-            token=args.token,
+                    'gw': self.gw,
-            sharding={
-                'number': args.shard_id,
-                'total': args.shard_count,
                 })
-        return inst
+            self.manhole.start()
 
     def run(self):
         """

disco/gateway/client.py

@@ -1,9 +1,10 @@
 import gevent
 import zlib
+import six
 
 from disco.gateway.packets import OPCode
 from disco.gateway.events import GatewayEvent
-from disco.util.json import loads, dumps
+from disco.gateway.encoding.json import JSONEncoder
 from disco.util.websocket import WebsocketProcessProxy
 from disco.util.logging import LoggingClass
 
@@ -14,9 +15,10 @@ class GatewayClient(LoggingClass):
     GATEWAY_VERSION = 6
     MAX_RECONNECTS = 5
 
-    def __init__(self, client):
+    def __init__(self, client, encoder=None):
         super(GatewayClient, self).__init__()
         self.client = client
+        self.encoder = encoder or JSONEncoder
 
         self.events = client.events
         self.packets = client.packets
@@ -48,10 +50,10 @@ class GatewayClient(LoggingClass):
         self._heartbeat_task = None
 
     def send(self, op, data):
-        self.ws.send(dumps({
+        self.ws.send(self.encoder.encode({
             'op': op.value,
             'd': data,
-        }))
+        }), self.encoder.OPCODE)
 
     def heartbeat_task(self, interval):
         while True:
@@ -90,7 +92,9 @@ class GatewayClient(LoggingClass):
 
     def connect_and_run(self):
         if not self._cached_gateway_url:
-            self._cached_gateway_url = self.client.api.gateway(version=self.GATEWAY_VERSION, encoding='json')
+            self._cached_gateway_url = self.client.api.gateway(
+                version=self.GATEWAY_VERSION,
+                encoding=self.encoder.TYPE)
 
         self.log.info('Opening websocket connection to URL `%s`', self._cached_gateway_url)
         self.ws = WebsocketProcessProxy(self._cached_gateway_url)
@@ -103,11 +107,12 @@ class GatewayClient(LoggingClass):
 
     def on_message(self, msg):
         # Detect zlib and decompress
-        if msg[0] != '{':
+        is_erlpack = ((six.PY2 and ord(msg[0]) == 131) or (six.PY3 and msg[0] == 131))
+        if msg[0] != '{' and not is_erlpack:
             msg = zlib.decompress(msg, 15, TEN_MEGABYTES).decode("utf-8")
 
         try:
-            data = loads(msg)
+            data = self.encoder.decode(msg)
         except:
             self.log.exception('Failed to parse gateway message: ')
             return
@@ -128,17 +133,20 @@ class GatewayClient(LoggingClass):
         if self.seq and self.session_id:
             self.log.info('WS Opened: attempting resume w/ SID: %s SEQ: %s', self.session_id, self.seq)
             self.send(OPCode.RESUME, {
-                'token': self.client.token,
+                'token': self.client.config.token,
                 'session_id': self.session_id,
                 'seq': self.seq
             })
         else:
             self.log.info('WS Opened: sending identify payload')
             self.send(OPCode.IDENTIFY, {
-                'token': self.client.token,
+                'token': self.client.config.token,
                 'compress': True,
                 'large_threshold': 250,
-                'shard': [self.client.sharding['number'], self.client.sharding['total']],
+                'shard': [
+                    self.client.config.shard_id,
+                    self.client.config.shard_count,
+                ],
                 'properties': {
                     '$os': 'linux',
                     '$browser': 'disco',

disco/gateway/encoding/__init__.py

@@ -0,0 +1,11 @@
+from .json import JSONEncoder
+
+ENCODERS = {
+    'json': JSONEncoder,
+}
+
+try:
+    from .etf import ETFEncoder
+    ENCODERS['etf'] = ETFEncoder
+except ImportError:
+    pass

disco/gateway/encoding/base.py

@@ -0,0 +1,14 @@
+from websocket import ABNF
+
+
+class BaseEncoder(object):
+    TYPE = None
+    OPCODE = ABNF.OPCODE_TEXT
+
+    @staticmethod
+    def encode(obj):
+        pass
+
+    @staticmethod
+    def decode(obj):
+        pass

disco/gateway/encoding/etf.py

@@ -0,0 +1,28 @@
+import six
+
+from websocket import ABNF
+from erlpack import Atom, unpack, pack
+
+from disco.gateway.encoding.base import BaseEncoder
+
+
+def make_keys_atom(obj):
+    res = {}
+    for k, v in six.iteritems(obj):
+        if isinstance(v, dict):
+            v = make_keys_atom(v)
+        res[Atom(k)] = v
+    return res
+
+
+class ETFEncoder(BaseEncoder):
+    TYPE = 'etf'
+    OPCODE = ABNF.OPCODE_BINARY
+
+    @staticmethod
+    def encode(obj):
+        return pack(obj)
+
+    @staticmethod
+    def decode(obj):
+        return unpack(obj)

disco/gateway/encoding/json.py

@@ -0,0 +1,22 @@
+from __future__ import absolute_import, print_function
+
+import six
+
+try:
+    import ujson as json
+except ImportError:
+    import json
+
+from disco.gateway.encoding.base import BaseEncoder
+
+
+class JSONEncoder(BaseEncoder):
+    TYPE = 'json'
+
+    @staticmethod
+    def encode(obj):
+        return json.dumps(obj)
+
+    @staticmethod
+    def decode(obj):
+        return json.loads(obj)

disco/gateway/events.py

@@ -1,5 +1,6 @@
 import inflection
 import skema
+import six
 
 from disco.util import skema_find_recursive_by_type
 from disco.types import Guild, Channel, User, GuildMember, Role, Message, VoiceState
@@ -22,21 +23,29 @@ class GatewayEvent(skema.Model):
 
     @classmethod
     def create(cls, obj):
-        self = cls(obj)
+        # If this event is wrapping a model, pull its fields
-        self.validate()
+        if hasattr(cls, '_wraps_model'):
-        return self
+            alias, model = cls._wraps_model
 
+            data = {
+                k: obj.pop(k) for k in six.iterkeys(model._fields_by_stored_name) if k in obj
+            }
+
+            obj[alias] = data
 
-def Sub(field):
-    class _T(GatewayEvent):
-        @classmethod
-        def create(cls, obj):
-            obj[field] = obj
         self = cls(obj)
         self.validate()
         return self
 
-    return _T
+
+def wraps_model(model, alias=None):
+    alias = alias or model.__name__.lower()
+
+    def deco(cls):
+        cls.add_field(alias, skema.ModelType(model))
+        cls._wraps_model = (alias, model)
+        return cls
+    return deco
 
 
 class Ready(GatewayEvent):
@@ -50,12 +59,13 @@ class Resumed(GatewayEvent):
     pass
 
 
-class GuildCreate(Sub('guild')):
+@wraps_model(Guild)
-    guild = skema.ModelType(Guild)
+class GuildCreate(GatewayEvent):
     unavailable = skema.BooleanType(default=None)
 
 
-class GuildUpdate(Sub('guild')):
+@wraps_model(Guild)
+class GuildUpdate(GatewayEvent):
     guild = skema.ModelType(Guild)
 
 
@@ -64,9 +74,8 @@ class GuildDelete(GatewayEvent):
     unavailable = skema.BooleanType(default=None)
 
 
-class ChannelCreate(Sub('channel')):
+@wraps_model(Channel)
-    channel = skema.ModelType(Channel)
+class ChannelCreate(GatewayEvent):
-
     @property
     def guild(self):
         return self.channel.guild
@@ -85,12 +94,13 @@ class ChannelPinsUpdate(GatewayEvent):
     last_pin_timestamp = skema.IntType()
 
 
-class GuildBanAdd(Sub('user')):
+@wraps_model(User)
-    user = skema.ModelType(User)
+class GuildBanAdd(GatewayEvent):
+    pass
 
 
-class GuildBanRemove(Sub('user')):
+class GuildBanRemove(GuildBanAdd):
-    user = skema.ModelType(User)
+    pass
 
 
 class GuildEmojisUpdate(GatewayEvent):
@@ -106,8 +116,9 @@ class GuildMembersChunk(GatewayEvent):
     members = skema.ListType(skema.ModelType(GuildMember))
 
 
-class GuildMemberAdd(Sub('member')):
+@wraps_model(GuildMember, alias='member')
-    member = skema.ModelType(GuildMember)
+class GuildMemberAdd(GatewayEvent):
+    pass
 
 
 class GuildMemberRemove(GatewayEvent):
@@ -136,16 +147,15 @@ class GuildRoleDelete(GatewayEvent):
     role = skema.ModelType(Role)
 
 
-class MessageCreate(Sub('message')):
+@wraps_model(Message)
-    message = skema.ModelType(Message)
+class MessageCreate(GatewayEvent):
-
     @property
     def channel(self):
         return self.message.channel
 
 
 class MessageUpdate(MessageCreate):
-    message = skema.ModelType(Message)
+    pass
 
 
 class MessageDelete(GatewayEvent):
@@ -177,8 +187,9 @@ class TypingStart(GatewayEvent):
     timestamp = skema.IntType()
 
 
-class VoiceStateUpdate(Sub('state')):
+@wraps_model(VoiceState, alias='state')
-    state = skema.ModelType(VoiceState)
+class VoiceStateUpdate(GatewayEvent):
+    pass
 
 
 class VoiceServerUpdate(GatewayEvent):

disco/state.py

@@ -57,8 +57,8 @@ class State(object):
     ----------
     EVENTS : list(str)
         A list of all events the State object binds too.
-    client : :class:`disco.client.DiscoClient`
+    client : :class:`disco.client.Client`
-        The DiscoClient instance this state is attached too
+        The Client instance this state is attached too
     config : :class:`StateConfig`
         The configuration for this state instance
     me : :class:`disco.types.user.User`
@@ -239,6 +239,7 @@ class State(object):
             member.guild = guild
             member.guild_id = guild.id
             guild.members[member.id] = member
+            self.users[member.id] = member.user
 
     def on_guild_role_create(self, event):
         if event.guild_id not in self.guilds:

disco/types/channel.py

@@ -2,7 +2,7 @@ import skema
 
 from holster.enum import Enum
 
-from disco.util.cache import cached_property
+from disco.util.functional import cached_property
 from disco.util.types import ListToDictType
 from disco.types.base import BaseType
 from disco.types.user import User
@@ -214,7 +214,7 @@ class MessageIterator(object):
 
     Parameters
     ----------
-    client : :class:`disco.client.DiscoClient`
+    client : :class:`disco.client.Client`
         The disco client instance to use when making requests.
     channel : `Channel`
         The channel to iterate within.

disco/types/message.py

@@ -2,7 +2,7 @@ import re
 import skema
 
 from disco.util import to_snowflake
-from disco.util.cache import cached_property
+from disco.util.functional import cached_property
 from disco.util.types import PreHookType, ListToDictType
 from disco.types.base import BaseType
 from disco.types.user import User

disco/util/cache.py

@@ -1,15 +0,0 @@
-
-
-def cached_property(f):
-    def getf(self, *args, **kwargs):
-        if not hasattr(self, '__' + f.__name__):
-            setattr(self, '__' + f.__name__, f(self, *args, **kwargs))
-        return getattr(self, '__' + f.__name__)
-
-    def setf(self, value):
-        setattr(self, '__' + f.__name__, value)
-
-    def delf(self):
-        setattr(self, '__' + f.__name__, None)
-
-    return property(getf, setf, delf)

disco/util/functional.py

@@ -0,0 +1,49 @@
+from gevent.lock import RLock
+
+
+def cached_property(f):
+    """
+    Creates a cached property out of ``f``. When the property is resolved for
+    the first time, the function will be called and its result will be cached.
+    Subsequent calls will return the cached value. If this property is set, the
+    cached value will be replaced (or set initially) with the value provided. If
+    this property is deleted, the cache will be cleared and the next call will
+    refill it with a new value.
+
+    Notes
+    -----
+    This function is greenlet safe.
+
+    Args
+    ----
+    f : function
+        The function to wrap.
+
+    Returns
+    -------
+    property
+        The cached property created.
+    """
+    lock = RLock()
+    f._value = None
+    f._has_value = False
+
+    def getf(*args, **kwargs):
+        if not f._has_value:
+            with lock:
+                if f._has_value:
+                    return f._value
+
+                f._value = f(*args, **kwargs)
+                f._has_value = True
+
+        return f._value
+
+    def setf(self, value):
+        f._value = value
+
+    def delf(self):
+        f._value = None
+        f._has_value = False
+
+    return property(getf, setf, delf)

disco/util/json.py

@@ -1,11 +0,0 @@
-from __future__ import absolute_import, print_function
-
-from json import dumps
-
-try:
-    from rapidjson import loads
-except ImportError:
-    print('[WARNING] rapidjson not installed, falling back to default Python JSON parser')
-    from json import loads
-
-__all__ = ['dumps', 'loads']

disco/voice/client.py

@@ -6,9 +6,9 @@ import time
 from holster.enum import Enum
 from holster.emitter import Emitter
 
+from disco.gateway.encoding.json import JSONEncoder
 from disco.util.websocket import Websocket
 from disco.util.logging import LoggingClass
-from disco.util.json import loads, dumps
 from disco.voice.packets import VoiceOPCode
 from disco.gateway.packets import OPCode
 
@@ -83,12 +83,13 @@ class UDPVoiceClient(LoggingClass):
 
 
 class VoiceClient(LoggingClass):
-    def __init__(self, channel):
+    def __init__(self, channel, encoder=None):
         super(VoiceClient, self).__init__()
 
         assert channel.is_voice, 'Cannot spawn a VoiceClient for a non-voice channel'
         self.channel = channel
         self.client = self.channel.client
+        self.encoder = encoder or JSONEncoder
 
         self.packets = Emitter(gevent.spawn)
         self.packets.on(VoiceOPCode.READY, self.on_voice_ready)
@@ -120,10 +121,10 @@ class VoiceClient(LoggingClass):
         })
 
     def send(self, op, data):
-        self.ws.send(dumps({
+        self.ws.send(self.encoder.encode({
             'op': op.value,
             'd': data,
-        }))
+        }), self.encoder.OPCODE)
 
     def on_voice_ready(self, data):
         self.state = VoiceState.CONNECTING
@@ -179,7 +180,7 @@ class VoiceClient(LoggingClass):
 
     def on_message(self, ws, msg):
         try:
-            data = loads(msg)
+            data = self.encoder.decode(msg)
         except:
             self.log.exception('Failed to parse voice gateway message: ')
 

docs/api.rst

@@ -14,10 +14,10 @@ version information for the installed package.
   versioning format. E.g. ``'5.4.3-rc.2'``
 
 
-DiscoClient
+Client
 ------------
 
-.. autoclass:: disco.client.DiscoClient
+.. autoclass:: disco.client.Client
       :members:
 
 

docs/index.rst

@@ -17,6 +17,7 @@ Contents:
 
   tutorial
   api
+  utilities
 
 Indices and tables
 ==================

docs/utilities.rst

@@ -0,0 +1,27 @@
+.. currentmodule:: disco
+
+Utilities
+=========
+
+This section details information about various utilities provided in the disco
+package, which aid the development and runtime management of disco clients/bots.
+Generally these utilties are situational, and can be enabled depending on
+various scenarious developers and users may find themselves in.
+
+Manhole
+-------
+
+The manhole utilty is a backdoor server that allows opening a interactive REPL
+while the client is running. This can be very useful for attaching and
+inspecting runtime state, without distribing the normal client operations. To
+enable the backdoor, simply set the
+:attr:`disco.client.ClientConfig.manhole_enable` setting, and tweak
+:attr:`disco.client.ClientConfig.manhole_bind` settings based on the connection
+parameters you'd like.
+
+It's recommended you connect to the manhole via ``rlwrap`` and ``netcat``, which
+will give a proper TTY-like readline experience. For example:
+
+.. sourcecode:: bash
+
+    rlwrap netcat localhost 8484