snips-skill

Helpers to keep Snips skills in Python3 free of boilerplate code.

Snips used to be a French company with a decent voice assistant. They were bought by Sonos and discontinued all services. Snips also created the Hermes MQTT protocol, which is compatible with the Rhasspy voice assistant.

A "skill" (in Snips parlance) is an MQTT client that may read sensors, do computations, or trigger devices.

Installation

pip install snips-skill

Requires Python 3.10+. Dependencies: paho-mqtt, pydantic, ply, croniter, toml, basecmd, decouple.

Contents

• Clients: MqttClient, CommandLineClient, SnipsClient, Skill
• Decorators: @topic, @intent, @min_confidence, @require_slot, @on_* session events
• State tracking: StateAwareMixin, @when, @conditional
• Scheduling: Scheduler, @cron, @delay
• Multi-room: MultiRoomConfig
• i18n: get_translations, room_with_article, room_with_preposition
• Utilities: expr (boolean expression parser)

Plain MQTT clients

MqttClient is a thin wrapper around paho-mqtt. CommandLineClient adds argument parsing for connection settings (-H, -P, -T, -u, -p) and standard logging.

Usage

from snips_skill import CommandLineClient, topic

class Logger(CommandLineClient):
    @topic('#')
    def print_msg(self, userdata, msg):
        self.log.info("%s: %s", msg.topic, msg.payload[:64])

if __name__ == '__main__':
    Logger().run()

@topic decorator

Registers a callback for an MQTT topic (supports wildcards). Methods receive (self, userdata, msg); standalone functions receive (client, userdata, msg).

@topic("hermes/intent/#", qos=0, payload_converter=decode_json)
def handler(client, userdata, msg):
    ...

Snips clients

SnipsClient

Reads connection parameters from /etc/snips.toml (or $SNIPS_CONFIG). Provides session lifecycle methods:

Skill

Base class for Snips actions. Extends SnipsClient with config.ini support:

from snips_skill import Skill, intent

class HelloSkill(Skill):
    @intent('example:hello')
    def say_hello(self, userdata, msg):
        return 'Hello, there'

if __name__ == '__main__':
    HelloSkill().run()

Session event decorators

All decorators can be used on methods (expect self, userdata, msg) or standalone functions (expect client, userdata, msg). Multiple decorators on the same method are supported; set log_level=None on all but one to avoid duplicate logs.

@intent decorator

@intent-decorated callbacks receive msg.payload as an IntentPayload object — a parsed version of the JSON intent data. Slot values are converted to appropriate Python types.

The session outcome depends on the return value or exception:

@min_confidence(threshold, prompt)

Rejects intents below a confidence threshold. If the confidence score is lower than threshold, the user is asked prompt to confirm. Default prompt: "Pardon?".

@require_slot(slot, prompt, kind)

Ensures a required slot is present in the intent. If missing, the user is asked prompt. Optionally checks that the slot matches a specific kind.

Example

@intent('example:set-temperature')
@min_confidence(0.5)
@require_slot('temperature', 'Which temperature?')
def set_temp(self, userdata, msg):
    temp = msg.payload.slot_values['temperature'].value
    return f"Setting temperature to {temp}"

State tracking

StateAwareMixin tracks the last known state of MQTT topics in self.current_state. Configure a status_topic in config.ini under the [global] section:

[global]
status_topic = status/#

Subscribes to that topic with JSON decoding; every message updates self.current_state and triggers any matching @when/@conditional handlers. The publish() method also avoids redundant updates — if the payload matches the current state, the message is suppressed.

Usage

from snips_skill import Skill, StateAwareMixin, when

class MotionLight(StateAwareMixin, Skill):
    @when('sensor/motion > 0')
    def light_on(self):
        self.publish('cmd/light', 'on')

@when decorator

Triggers the handler whenever a boolean condition becomes true:

@when('sensor/motion > 0')
def motion_detected(self):
    ...  # switch light on

@conditional decorator

Triggers the handler whenever a relevant topic changes, passing True/False:

@conditional('sensor/temperature > 25 or sensor/humidity > 80')
def uncomfortable(self, on):
    if on:
        ...  # turn on AC
    else:
        ...  # turn off AC

Boolean expressions support comparisons (<, >, <=, >=, ==, !=, ~= regex), and, or, not, and parentheses.

Boolean expression grammar

The expression parser (expr.py) supports a simple grammar for use with @when and @conditional:

expr       → term
           | expr AND expr
           | expr OR expr
           | NOT expr
           | LPAREN expr RPAREN

term       → TOPIC LESS NUMBER
           | TOPIC LESS_EQUAL NUMBER
           | TOPIC GREATER_EQUAL NUMBER
           | TOPIC GREATER NUMBER
           | TOPIC EQUAL literal
           | TOPIC NOT_EQUAL literal
           | TOPIC REGEX_MATCH STRING

literal    → NUMBER | STRING

Precedence (highest to lowest): NOT > comparisons > AND > OR. See snips_skill/test_expr.py for examples.

Task scheduling

Scheduler mixin adds cron-style and delayed task execution.

@cron decorator

Run a method on a cron schedule:

from snips_skill import Skill, Scheduler, cron

class MySkill(Scheduler, Skill):
    @cron("0 6 * * *")   # every day at 6:00
    def morning_routine(self):
        ...

@delay decorator

Delay method execution by a duration (with optional randomization):

from snips_skill import delay

@delay(minutes=5, randomize=True)
def deferred_action(self):
    ...

Multi-room support

MultiRoomConfig maps site IDs to room names from config.ini sections. Each section with a site_id option (except [global] and other standard sections) becomes a named room:

[global]
status_topic = status/#      # not related to rooms; used by StateAwareMixin

[kitchen]
site_id = main
some_option = value

[bedroom]
site_id = bedroom
another_option = 42

from snips_skill import MultiRoomConfig

class MultiRoomSkill(MultiRoomConfig, Skill):
    LOCATION_SLOT = 'room'

    def handle_intent(self, payload):
        room = self.get_room(payload)
        config = self.get_room_config(payload)
        site = self.get_site_id(payload)

Key methods: get_room(), get_current_room(), get_room_name(), get_room_config(), get_site_id(), all_rooms(), in_current_room().

Internationalization

Internationalization uses Python's standard gettext module. Run xgettext on your Python sources to produce a .pot template file, then create .po files for each locale and compile them to .mo files:

your-skill/
├── locale/
│   ├── my_skill.pot                 # template (generated by xgettext)
│   ├── de_DE/
│   │   └── LC_MESSAGES/
│   │       └── my_skill.mo         # compiled from my_skill.po
│   └── fr_FR/
│       └── LC_MESSAGES/
│           └── my_skill.mo
└── skill.py                         # calls get_translations(__file__, "my_skill")

The .po file format follows standard gettext conventions:

# my_skill.po
msgid "the kitchen"
msgstr "die Küche"

msgid "in the kitchen"
msgstr "in der Küche"

See the Makefile for the workflow used by this library: make messages generates the .pot file from source, and make dist compiles .po to .mo before building.

After installing translations with get_translations(__file__, "my_skill"), helper functions provide translated room names with articles and prepositions (supports gendered languages like German):

from snips_skill import room_with_article, room_with_preposition

room_with_article("kitchen")       # "the kitchen" / "die Küche"
room_with_preposition("kitchen")   # "in the kitchen" / "in der Küche"