[systemd-devel] sd_bus_add_match callback

[Giacinto Cifelli]

hi Lennart,

On Fri, Apr 10, 2020 at 2:14 PM Lennart Poettering
<lennart at poettering.net> wrote:
>
> On Do, 09.04.20 14:12, David J (emacsd at icloud.com) wrote:
>
> > Hello Systemd developers!
> >
> > > I asked this question earlier but I haven’t gotten any reply so I thought asking again.
> >
> > > Question regarding sd_bus_add_match (sd-bus.c):
> > >
> > > Is there any bad consequences to use the same callback for
> > > multiple signal match and then using the userdata parameter to
> > > distinguish among the different signals? See the sample code below
> > > for a reference of what I am trying to do.
>
> No sure why one would do that, but the userdata argument is something
> you can use any way you like. Most people stick some context object
> pointer in it, but it's entirely fine to place anything else there,
> for example an enum that you cast to a pointer.

If I understand correctly David's question, he wants to know if he got
triggered twice on the same event in a single client.
I am also interested because it could be simple for some application
to be triggered by two events instead than re-firing a message
internally.

>
> Lennart
>
> --
> Lennart Poettering, Berlin
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Thank you,
Giacinto