Re: your mail

Jon Berry (
Fri, 21 Nov 1997 14:48:23 -0500 (EST)

I suspect that you haven't called the function yet. The code you have
below *defines* the function. To call it:

1. click with the left button in a graph window
2. (at STk>) (forefather-binding (current-graph-view))

now you should be able to click on a vertex, hit the "f" key, and see
its forefather flash.

Note that STk provides you with Scheme, a standard functional programming
language. The standard is available at:

and other places.

It would be a good idea to spend an hour or two looking at the language.
Then the STk manual would be good reading to gear up for manipulating


Dr. Jon Berry Office: Whitley 204
Assistant Professor, Computing Sciences Campus Box: 2130
Elon College, N.C. 27244 Office Phone: (910)584-2290

On Fri, 21 Nov 1997, Graph Theory Project wrote:

> Hi:
> last time I asked you about the articel" Graph Drawing and ..."
> Figure 6, after I draw a picture, and typed:
> (define (forefather-binding graph-view)
> (strongly-connected-components (graph graph-view))
> (bind (slot-ref graph-view 'graph-toplevel) "<KeyPress-f>"
> (lambda (x y)
> (flash (vertex-item
> (find-vertex-attribute 'forefather
> (slot-ref (car *link:selected-vertex-item*) 'vertex))graph-view)))))
> then it appeared the #undefined
> then I click one vertice on the graph, and type f, there is nothing happened.
> I do not know why, I tried two types to type f, first on graph, I just type key
> f, second I type f on STK>, third I type f on stk then return, it appeared
> there is error, I do not know why?
> best wishes!
> Mei Liu