Scheme Your Windows

Installing SCWM
Downloading and Building
XNested Setup
GDS for Interaction

Installing SCWM




Downloading and Building

A working version of SCWM can be obtained from sourceforge CVS. Compilation is much more straightforward than one would suspect from a project so old (thanks to dsmith for doing the painful parts of unbitrotting). The standard autoconf sequence of commands should work.

sudo make install


The directory sample.scwmrc has a few sample SCWM configurations. system.scwmrc and sample.scwmrc both work fairly well; I have yet to test the others. If not using system.scwmrc it is useful to at least include the bits that enable debugging.

(define debug #t)

(if debug
      (add-hook! module-loaded-hook display-module-loaded)
      (set! %load-verbosely #t)
      (debug-enable 'debug 'backtrace)
      (read-enable 'positions)))

SCWM will attempt to load system.scwmrc by default, but this can be overridden with the -f option. The default system.scwmrc loads user config from a series of files in ~/.scwm/.


XNested Setup

The easiest way to hack on SCWM is to run it inside of Xnest.

Xnest :1 &
scwm --display :1 --debug # --debug makes X requests synchronous

GDS for Interaction

SCWM has an emacs interaction mode that communicates with the window manager using X window properties, but the emacs side of the code doesn't quite work, and GDS is featureful enough now to be used to interact with scwm. Using GDS makes hacking scwm quite a bit easier. GDS requires a Guile built with threads to work properly (the version in Debian is built without threading).

scwmrc code

The following code should be in your scwmrc somewhere.

(use-modules (ice-9 gds-client)
             (ice-9 threads))

;;; GDS thread (in case it must be killed during debugging, ...)
(define cke-gds-thread #f)

(define (connect-to-debugging-server)
  (set! cke-gds-thread
        (call-with-new-thread (lambda () (run-utility))))

After defining you can either use scwmrepl to run (connect-to-debugging-server) after starting a GDS server, or simply add (connect-to-debugging-server) to the config if one will always be running.

Emacs config

I wrote a bit of elisp to simplify setting up a scratch buffer for interaction with guile.

(require 'gds)
(require 'gds-server)
(require 'gds-scheme)

(defvar guile-scratch-buffer-name "*guile-scratch*"
  "Name of the Guile evaluation scratch buffer")

(defun make-guile-scratch-buffer ()
  (let ((scratch-buf (generate-new-buffer guile-scratch-buffer-name)))
    (switch-to-buffer scratch-buf)

If you were already running a debugging client process you will need to choose the process to associate the buffer with; ps will tell you the PID of scwm.

Known Issues

Occasionally evaluating an expression or viewing a backtrace will make scwm lockup. My understanding is that scwm is not threadsafe, and there are some evil issues that will take a while to solve. GDS works well enough for now; if I can't make GDS completely reliable I shall unbitrot the scwm emacs interaction mode (unless someone else beats me to it, hint hint).

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Last Modified: January 21, 2013