How to subscribe to events emitted from a plugin?

[michaelfung]

I want to emit some event, say foo, inside a plugin:

# inside a plugin module:
sub register ($self, $app, $conf) {
  ...
   $self->emit(foo => $event_data);

How can I subscribe to the foo event at some other parts of the app?

[guest20]

You want the plugin to register a helper that makes $self available. If it's not your plugin you can just sub-class it and add the helper yourself.

# inside a plugin module:
sub register ($self, $app, $conf) {
  ...
   $app->helper(pluginName => sub { $self }); 

#elsewhere: 
$c->pluginName->on(...)

... it might be a bit late if the plugin emits an event during register though

[michaelfung]

I have thought about this but I am hoping for something more neat like:

my $myplugin = $plugin_manager->get_instance('MyPlugin');
$myplugin->on(foo => sub { ... });

My use case is: a MQTT plugin emit some topic message events, then I can add other plugins later when needed to inteface with Thingspeak, IFTTT, Matrix ...etc.

I believe we have to live with this solution for now. Thanks.