$Id: scwm-faq,v 1.6 1999/11/23 20:41:42 gjb Exp $

Scwm Frequently Asked Questions
-------------------------------
Last Updated 12-Nov-1999

* How can I find out more about Scwm?

Web Page:      http://scwm.mit.edu/

Mailing list:  scwm-discuss-request@mit.edu, body (not subject) of "subscribe"
               scwm-discuss@mit.edu to post to the list

  Mailing list
  Archived at: http://scwm.mit.edu/scwm-discuss.1998/
               http://scwm.mit.edu/scwm-discuss.1999/

Documentation: http://www.cs.washington.edu/homes/gjb/scwm-doc/


Q: How do you pronounce Scwm?

A:

Some spell it out: "Ess See Double-you Emm", others pronounce it as
an acronym "squim" or "skwim" rhyming with "whim" starting with the
"squ" as in "squat".


Q: How can I convert by .fvwm2rc to a .scwmrc?

A:

Unfortunately, right now there are no automatic tools for doing the
conversion (we'd love to see someone contribute such a thing).  A more
complete answer is that you probably do not want to directly convert
your .fvwm2rc to a .scwmrc because Scwm permits so much greater
abstraction and programmability that a simple conversion is likely to
not be a very good .scwmrc.

We recommend that you take one of the existing .scwmrc files from the
sample.scwmrc/ directory, and modify it to suit your needs.  We are
working for easier-to-use GUI configuration tools, but they are not yet
in place.


Q: What's the difference between:

     (menuitem "A&bout Scwm" #:image-left "mini-exclam.xpm" 
 	      #:action (thunk scwm-about-message))
 
                and
 
     (menuitem "A&bout Scwm" #:image-left "mini-exclam.xpm" 
 	      #:action scwm-about-message)

A:

To understand this, you need to understand what the `thunk' macro does:

(defmacro-public thunk (proc)
  `(lambda args (apply ,proc args)))

This means that:

(thunk scwm-about-message)

expands into an #:action of

(lambda args (apply scwm-about-message args))

The second menuitem you mention above has an action of just
`scwm-about-message'.  The big difference between these two ways of
specifying an action procedure is which scwm-about-message procedure is
invoked when the menuitem is selected.

In the first case (with the thunk), each time the menuitem is clicked
the currently visible binding for the symbol `scwm-about-message' will
be invoked.  In the second case, whatever binding `scwm-about-message'
has when the menuitem is created will be used.

Often (and in normal use, really), the two possibilities above
coincide. There are two primary cases where they differ:

1) in the second case (w/o the thunk), the symbol scwm-about-message
*must* be bound when the menuitem object is created.  That is, the
definition of scwm-about-message must precede the creation of the
menuitem.  In the first case w/ the thunk, the lambda that the thunk
expands into avoids this dependency since the symbol evaluation is
deferred until execution of the menuitem's action; so with the thunk,
the procedure definition can come after the menuitem definition.

2) If scwm-about-message is rebound (e.g., you change it's definition,
or edit the module in which it is defined and re-load the module), then
the first version (using thunk) always gets the current binding (for
better or worse), while the second version always executes the same old
procedure (though any of the procedures called by that procedure are
looked up freshly; note that the lambda generated by the thunk macro
just adds a level of indirection so the top level procedure is one of
those called procedures).


Q: What's the difference between `define' and `define-public'

A:

The only time it matters is when you consider the Guile module system. A
define-public makes a definition that's part of the interface of a
module, whereas a define makes a definition that's local.  In your
startup files it makes little difference, but once you start writing
modules, you need to be sure to use define-public or define*-public when
you want other modules to have access to that procedure's functionality.


Q: Where can I learn more about Scheme?

A:

See Greg's Scheme lecture notes at:

http://www.cs.washington.edu/education/courses/341/99su/lectures/scheme/


Q: How do I change the SCWM_LOAD_PATH after Scwm has been started, say in
my .scwmrc startup file?

A:

The SCWM_LOAD_PATH environment variable is only used at startup time to
initialize the %load-path Guile variable.  You should edit this directly 
using, e.g.,

(set! %load-path (cons (string-append (getenv "HOME") "/.scwm/modules") %load-path))

or 

(append! %load-path (list (string-append (getenv "HOME") "/.scwm/modules")))