Tagging Message Filter Rules

[Lawrence D'Oliveiro]

One thing missing from the D-Bus message filtering API is any indication
of which rule, if there is more than one, is the reason for your seeing
a particular message. The only way I could see to do this was to
implement my own interpreting of filtering rules and comparison with
incoming messages.

To demonstrate this in action, I added a new “tagged_listener” script
to my DBussy examples repo <https://github.com/ldo/dbussy_examples>,
<https://gitlab.com/ldo/dbussy_examples>. This one does nothing more
than display a custom message associated with each filter rule, but it
should be sufficient to show the idea.