webthing-python/webthing/value.py at master · WebThingsIO/webthing-python · GitHub

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"""An observable, settable value interface."""

from pyee import EventEmitter

class Value(EventEmitter):

"""

A property value.

This is used for communicating between the Thing representation and the

actual physical thing implementation.

Notifies all observers when the underlying value changes through an

external update (command to turn the light off) or if the underlying sensor

reports a new value.

"""

def __init__(self, initial_value, value_forwarder=None):

"""

Initialize the object.

initial_value -- the initial value

value_forwarder -- the method that updates the actual value on the

thing

"""

EventEmitter.__init__(self)

self.last_value = initial_value

self.value_forwarder = value_forwarder

def set(self, value):

"""

Set a new value for this thing.

value -- value to set

"""

if self.value_forwarder is not None:

self.value_forwarder(value)

self.notify_of_external_update(value)

def get(self):

"""Return the last known value from the underlying thing."""

return self.last_value

def notify_of_external_update(self, value):

"""

Notify observers of a new value.

value -- new value

"""

if value is not None and value != self.last_value:

self.last_value = value

self.emit('update', value)

webthing-python/webthing/value.py at master · WebThingsIO/webthing-python · GitHub

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