From: "Jan D." <Jan.Djarv@mbox200.swipnet.se>
Cc: emacs-devel@gnu.org
Subject: Re: Session management patch, please comment.
Date: Thu, 21 Feb 2002 20:57:35 +0100 (CET) [thread overview]
Message-ID: <200202211957.UAA00205@gaffa.gaia.swipnet.se> (raw)
In-Reply-To: <5xit8rwywv.fsf@kfs2.cua.dk> "from Kim F. Storm at Feb 20, 2002 11:50:40 pm"
> Jan Djärv <Jan.Djarv@mbox200.swipnet.se> writes:
>
> > > What about this approach:
> > >
> > > In C, you declare a hook variable emacs-session-save-function.
> > >
> > > In Lisp, you bind a save-session-state function to this variable.
> > >
> > > When the save_yourself event arrives, the function bound to
> > > emacs-session-save-function is called (with whatever arguments you
> > > think it needs).
> >
> > I don't quite understand. What purpose does the
> > emacs-session-save-function serve, why not call a lisp function
> > directly? And if one can call lisp functions, why not call the
> > functions in save-session-state-hook from C?
>
> I believe the normal approach when calling lisp functions from C is to
> run a hook, i.e. call the function(s) bound to a variable defined in C.
>
> By doing that, you don't require lisp functions to have a specific
> name (or being defined), and it uses a well-defined method to invoke a
> lisp function from C.
Okay.
> > The reason I did it the way presented, is was I think you can't call
> > lisp functions from the X event input handler. Thus an Emacs event is
> > used to get control to the lisp part.
>
> Using `special-event-map' as you do is the right approach (I think).
> The only thing I suggest to change is to define the handle-save-yourself
> function in C.
>
> It should call the function bound to the variable `emacs-session-save-function'
> (that function is written in lisp and runs the save session hooks), and
> depending on whether that function returns nil or t, it will execute the
> relevant parts of the code currently located in x-sm-interact-done.
>
> That way, you don't need the x-sm-interact-done callback from lisp to C.
Right, now I see. I didn't think about that. Good idea.
But if handle-save-yourself is in C, it should be able to call the save
session hooks by itself, and then do what x-sm-interact-done does, could
it not? That way, less code (marginal) and more straight forward logic
is achived.
I'll send an updated patch shortly.
>
> > >
> > > In general, I would suspect that you only need to know either the
> > > previous session id (when doing restore), or the current session id
> > > (when doing save).
> >
> > If you have saved state in a file with a filename based on the previous id,
> > you presumably would want remove or move that file, either when
> > doing restore or save session.
>
> Ok, but if that is necessary, you can save the `session-id' parameter
> (of the restore function) in a variable defined in lisp - to be used
> later by the save function.
>
> However, I would expect the restore function to remove that file.
> But again, that would be decided in lisp rather than the core emacs
> functions.
I just wanted to make all info available. I haven't looked at other
implementations so I really don't know what the convention is.
Jan D.
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next prev parent reply other threads:[~2002-02-21 19:57 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-02-17 19:11 Session management patch, please comment Jan D.
2002-02-19 6:37 ` Richard Stallman
2002-02-19 8:40 ` Kim F. Storm
2002-02-19 20:13 ` Jan D.
2002-02-19 20:12 ` Jan D.
2002-02-19 22:43 ` Kim F. Storm
2002-02-20 20:29 ` Jan Djärv
2002-02-20 22:50 ` Kim F. Storm
2002-02-21 19:57 ` Jan D. [this message]
2002-02-21 21:18 ` Kim F. Storm
2002-02-26 22:49 ` New session management patch Jan D.
2002-02-27 5:51 ` Richard Stallman
2002-02-27 10:23 ` Eli Zaretskii
2002-02-27 15:25 ` Andreas Schwab
2002-02-27 18:11 ` Colin Walters
2002-02-28 4:08 ` Richard Stallman
2002-02-27 19:43 ` Jan D.
2002-02-28 18:22 ` Richard Stallman
2002-02-28 15:36 ` Kim F. Storm
2002-03-01 1:11 ` Richard Stallman
2002-02-22 4:32 ` Session management patch, please comment Richard Stallman
2002-02-20 22:13 ` Richard Stallman
2002-02-21 20:01 ` Jan D.
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