Re: [gtk-list] Re: Multiple main loops

[Scott Dattalo <sdattalo unix sri com>]

On 18 Jun 1999, Owen Taylor wrote:

> Scott Dattalo <sdattalo@unix.sri.com> writes:
> 
> > I'm writing a gui wrapper around my currently command-line-interface only
> > program and am having a problem with more than one library wanting to be
> > the 'main loop'. Specifically, I'm using the readline library for the CLI
> > and then I'm also using gtk for the gui api. Each requires complete
> > control of the process. I thought I had solved this problem with pthreads.
> > In other words, I have a main pthread that spawns two child threads and
> > runs the gtk loop in one and the readline loop in the other. It sorta
> > works. However, 1) It always SEGVs when it exits and 2) It occasional gets
> > X, gdk, and/or shmem errors. 
> 
> Instead of trying to answer the questions about threads,
> etc, let me point out that you can make readline()
> use the GTK+ main loop.
> 
> See rl_callback_handler_install() in the readline documentation.

Correct me if I'm wrong, but... doesn't this imply that a gtk widget is
receiving keys and redirecting them to readline via callback interface? In
my case, the readline library is receiving it's input from stdin (from the
terminal in which the processs was invoked). In other words, for now the
textual base of my program runs in an xterm (actually Eterm :)) while the
graphical portion runs in a GtkWidget widget (that contains other
widgets...). The keypress events for the various GtkWidgets are
automagically routed to the proper places. When the terminal receives
focus, then the keypress events are directed to readline (via stdin).
Hence, to make the call back process work, I would have to be able to
capture the keypress events for the xterm. Is this correct? And if so, the
next obvious question is how?


On Fri, 18 Jun 1999, Paul Barton-Davis wrote:
> >In other words, I have a main pthread that spawns two child threads and
> >runs the gtk loop in one and the readline loop in the other. It sorta
> >works. However, 1) It always SEGVs when it exits and 2) It occasional
gets
> >X, gdk, and/or shmem errors.
> >
> >
> >This subject was brought up a few weeks ago, but unfortunately the
archive
> >is currently down...
>
> are you making GTK calls from the non-GTK thread ? you can't do this
> safely unless you wrap the GTK calls in GTK_THREAD_{ENTER,LEAVE} or
something
> like that.

One of the reasons I chose threads over forking is so I wouldn't have to
deal with shared memory details. So to answer your question, yes I'm
making gtk calls from non-gtk threads (and liberally exchanging data
between the two) and no I'm not using the GTK_THREAD macros. I will look
into this, however I'd like to do away with threads and use the
signals-only-approach if it's possible. Thanks. 

Scott