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Re: signal handling bogosities


From: Richard Stallman
Subject: Re: signal handling bogosities
Date: Thu, 02 Jan 2003 13:38:12 -0500

    > The XEmacs developers told me 10 years ago that XEmacs used an
    > inside-out structure, where Xt implements the event loop and calls
    > Emacs to handle each events.  That unnatural structure makes it
    > impossible to write your own loop in Lisp.  I rejected it.

    One could argue that for a GUI application the XEmacs approach is the
    natural loop :-)

It prevents the Lisp code from being natural.  That is more important.
The natural structure for an event loop in Lisp is

  (while ...
    (let ((input (read-events-somehow)))
      (execute input)))

Any change in Emacs that would prevent the Lisp code from looking like
this has a major drawback.

    I haven't looked at this in detail, but it seems to me that a lot could be
    gained if Emacs could wait for events in some toolkit specific routine,
    like XtAppNextEvent for Xt.

Emacs needs to wait for input from various descriptors at the same
time, adn with a timeout.  If it is possible to do that with
XtAppNextEvent, then it is possible to use XtAppNextEvent.




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