enthought/envisage — comment on commit a58e58b5fbaf99dd0e29874967743846b4ea6d78
File:  line 0
By mchilvers:

Back to the smell...The service offer shouldn't be the actual event manager, just a factory to create it when somebody asks for it. If you want the 'event_manager' trait to save doing the service lookup everytime you need the event manager then you could either a) create a new subclass of Application that has a trait property that does the required lookup, b) make your plugin contribute a Category to add the appropriate trait to the
Application class... b) might be a bit nicer but it basically does what you do now, only in a more formal and obvious way...