Re: again: x11 is eating one character from stdin pipe

[Ethan M. <merritt@u.washington.edu>]

On Monday 27 October 2003 07:04, Petr Mikulik wrote:
> I'd a look to the patch of June 21 which made the break; even though I
> don't understand it, I've found that commenting out the
> "X11_waitforinput();" call does not produce the forgetting-pipe error:
>
>    /* Force default font at start of plot */
> #ifdef USE_MOUSE
>     /* EAM June 2003 - Flush the set font command through the pipe */
>     /* to gnuplot_x11, then wait for it to return the resulting    */
>     /* font size information (v_char and h_char).                  */
>     if (!default_font_size_known) {
>         X11_set_default_font();
>         FFLUSH();
>         X11_waitforinput();
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>         default_font_size_known =3D TRUE;
>     }
> #else
>     X11_set_default_font();
> #endif
>     X11_set_font("");
> }
>
>
> Does that command have to be there?

Well yes.  That is the whole point of the excercise.
The idea is to give X11 a chance to initialize the window data
structure and send back sizing and font information before
proceeding.  That way the plot can be laid out correctly.

Daniel J Sebald <dan...@ie...> wrote>
>That is some strange code, however. =20

I will choose to take that as a compliment :-)

>Does anyone know what the basic concept is here?

See above.=20

> Maybe a handshaking scheme is needed.  Perhaps x11.trm

Handshaking didn't help.  What was needed was an interlock.
I added that to CVS on 23 Oct.  You should not (I hope!!) be
seeing problems with Octave any more.   If you are then=20
please send me another sample script that generates the
error.

As I previously noted, there is a separate problem with
buffered/unbuffered input streams.   Awk is not happy=20
with the unbuffered stream.  I don't know why, and I don't
know what other scripting environments might suffer from
the same problem.

--=20
Ethan A Merritt       merritt@u.washington.edu
Biomolecular Structure Center Box 357742
University of Washington, Seattle, WA 98195