Registering device events in a plugin

I have been looking into alternatives for the polling loops I end up using in most of my plugins... One thing that could help would be registering for device state changes internally, rather than a visible Trigger in Indigo. Effectively, it would be a simple callback registered for a device that allows another plugin to see state changes.

I've been using the EventHook example in several other Python projects, which is very effective for this kind of thing. I'm sure there are other ways to handle this in Indigo, just throwing it out as an example of what I'm looking for.

So a simple use could be:

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# plugin.py

    def deviceStartComm(self, device):
        device.onStateChange += self.deviceStateChanged

    def deviceStateChanged(device, stateName):
        self.logger.debug('State Change: %s[%s] => %s', device.name, stateName, device.states[stateName])



Any thoughts on such a thing?

If you do this in your startup():

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        indigo.devices.subscribeToChanges()


Then you can do something like:

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    def deviceUpdated(self, oldDevice, newDevice):
        indigo.PluginBase.deviceUpdated(self, oldDevice, newDevice)

        for masqDeviceId, masqDevice in sorted(self.masqueradeList.iteritems()):
            baseDevice = int(masqDevice.pluginProps["baseDevice"])
            if oldDevice.id == baseDevice:
                self.updateDevice(masqDevice, oldDevice, newDevice)


Or am I misunderstanding that you're wanting to do?

[jay (support)]

Yep, I think you want subscribeToChanges() so that your deviceUpdated method gets called for every device that has a change. You can then decide if the change is one you're interested in or not.

Good pointer... That is along the lines of what I was trying to do. Now I need to think about how it fits in my plugin architecture

Good pointer... That is along the lines of what I was trying to do. Now I need to think about how it fits in my plugin architecture

I'm confused about something - from your original code post, it looks like you're trying to catch changes to states for the plugin's own devices. Since the ONLY thing that can change the states of a plugin device is the plugin itself, why do you need this in the first place? Do you have deferred processing you need to do after devices have changed?

Yeah, that was a simple example just to demonstrate a trivial case, but doesn't model what my plugin is doing...

A better example would be:

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<!-- Devices.xml -->
    <Name>Master Controller</Name>
    <ConfigUI>
      <Field type="list" id="devices">
        <Label>Remote Devices:</Label>
        <List class="indigo.devices" filter="indigo.dimmer"/>
      </Field>
    </ConfigUI>


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# plugin.py
    def deviceStartComm(self, device):
        for remoteDevice in device.pluginProps['devices']:
            # set up event hook for device state changes
            remoteDevice.onStateChange += self.deviceStateChanged

    # custom event hook for device state changes
    def deviceStateChanged(device, stateName):
        self.logger.debug('State Change: %s[%s] => %s', device.name, stateName, device.states[stateName])


I'm still playing around with subscribeToChanges() to see if I can make it work for this case. In my case, each custom device is watching for only the external devices it cares about, not so much the devices created by the Plugin.

[jay (support)]

That's exactly what the Virtual Devices interface does for it's devices (and many of the other plugins that do that kind of thing). The plugin maintains a list of devices for which changes are important (built and maintained during deviceStartComm and deviceStopComm). It subscribes to changes, then in the deviceUpdated method looks at the device to see if it's one it cares about. If so, it does whatever work is necessary. If not, it just passes.

Thanks for the help, gents. I've added basic support for device changes to my plugin framework and will use that going forward. I'd still like to improve it a bit for capturing specific events, but that may come at a later time

In case you are curious, here is the base I usually use for building plugins:
https://github.com/jheddings/indigo-iplug