[cl-graph-devel] cl-graph symbol it has no value

[Andrej Mošať]

Hi,
thanx for programming this huge package.
I`m working on a scientific project involving optimization of huge sets of
interconnected chemical reactors.
2 questions in order to get the wheels turning for a newbie:

tried running the code:

(let ((g (make-container 'graph-container)))
  (loop for v in '(a b c d e) do
        (add-vertex g v))
  (loop for (v1 . v2) in '((a . b) (a . c) (b . d) (c . e)) do
        (add-edge-between-vertexes g v1 v2))
  g)

and got this:

#1=#:|616 623 (DEFMETHOD FIND-VERTEX (# # &OPTIONAL ...) ...)-62-1-1|:
symbol IT has no value
   [Condition of type SYSTEM::SIMPLE-UNBOUND-VARIABLE]

found line 618 in graph.lisp:
(defmethod find-vertex ((graph basic-graph) (value t)
                        &optional (error-if-not-found? t))
  (aif (find-item (graph-vertexes graph) (funcall (vertex-key graph) value))
       it
       (when error-if-not-found?
         (error 'graph-vertex-not-found-error :vertex value :graph graph))))


and I have no idea what the symbol "it" means, or where should I look for
it.

Second question is about a use-case

can I make a directed graph with the following structure and how?

A D
B D
C D
D E
G E
E F
E J
J H

Is the cl-graph package only for exporting the graphs to dot format, or can
you do more stuff with the graphs? Where can I find more tutorials? (the one
on uncommon wiki was not suitable for my simple use case). Can you use a
graph as a data-structure ? Can you traverse and search the directed graph?
A simple (even uncommented) tutorial would be much appreciated.

Thanks a lot, happy coding
-- 
Andrej Mošať
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mailman.common-lisp.net/pipermail/cl-graph-devel/attachments/20080610/701270f5/attachment.html>