Re: [AUCTeX-devel] Auctex, synctex and Evince

[Ralf Angeli]

* Jose Aliste (2010-06-13) writes:

> On Sat, Jun 12, 2010 at 2:09 PM, Ralf Angeli <address@hidden> wrote:
>
>> In AUCTeX one can carry out a function instead of simply executing a
>> command line when calling a viewer.  If the function can incorporate the
>> logic hinted at above, then supporting DBUS should be no major problem.
>> However, at least the forward search works fine via the command line at
>> the moment.  What would be gained to implement it with DBUS?
>
> The main reason is interoperability/ portability IMO. The main thing
> about DBUS is that you get a fine control of the viewer. For instance,
> you would call Evince only the first time, and then use DBUS to do the
> forward search whenever you need to.

Well, yes, but this is already working with the command line interface.
At least for opening a certain page.  When Evince is asked to open a
document that is already being displayed, it is not opened in a new
Evince instance but the displaying instance will switch to the requested
page.

Also, I just checked the Evince sources and in
<URL:http://git.gnome.org/browse/evince/tree/configure.ac> it looks as
if D-Bus support can be disabled.  So it is not guaranteed that D-Bus is
available which would make the method with command line calls the more
robust one.  I am not sure, though, if the behavior above described
works if D-Bus is not available.

> DBUS is IMO the right way to go.
> You could of course add new command line options to evince so that not
> only you open the link in a page but also you highlight the
> corresponding part in the pdf/dvi (and the first patches to evince did
> that), but you would expose parameters that a normal user should not
> known/use (from the point of view of Evince).

It probably depends on how convoluted the arguments to be given on the
command line can get.

> For backward search, in emacs you would listen to the DBUS signal
> evince emits, and highlight the source that corresponds.

Yep.  Since I don't know the D-Bus implementation in Emacs very well, I
am not sure if it offers some methods which could be used for that per
default.  Skimming through the Emacs D-Bus manual I could not find any.

> Evince just
> does not know which editor you are using, so the support is not tied
> to any editor. You could do this again, using the command line,
> passing the editor cmd to evince when you call it, but it seems a
> little akward to do it this way (again, in my opinion).

Actually this is the way inverse search has worked between Emacs/AUCTeX
and xdvi for years.  So for me this does not seem very awkward. (c;

Anyway, if somebody is interested in implementing support for
D-Bus-based communication with Evince (and perhaps other viewers) I
would not argue against it.  (Even though I don't see the immediate
benefits compared to the command line interface.  But that's probably
just because Evince did this so well for forward search. (c;)  But we
should keep the command-line-based communication as a fallback.

-- 
Ralf