Subj : Re: Flowchart software that supports top down development?
To   : comp.programming
From : Richard Heathfield
Date : Fri Jul 29 2005 07:56 pm

Roman Mashak wrote:

> Hello, Richard!
> You wrote  on Wed, 27 Jul 2005 08:12:19 +0000 (UTC):
> 
>  RH> No, but I can think of an easy way to do it yourself.

<snip>

> Does this technique suppose to prepate this sort of file manually?

That wasn't my intent (although Phlip has already indicated that it could 
easily be done that way).

Rather, I was presuming that the code to generate the file would be included 
in the program itself.

Let me give you an example in the mythical language "CODEX" (which is a 
brand new programming language of my own invention, primarily characterised 
by the fact that you make up the syntax as you go along, which makes it 
impossible to implement but quite handy for language-blind Usenet 
discussions!):

PROC LogLabel PARMS String name, Flag stub ENDPARMS
  IF genflow
    ECHO genflow, "  "
    ECHO genflow, name
    ECHO genflow, " [label=\""
    ECHO genflow, name
    ECHO genflow, "\" fontcolor=\"white\" color=\""
    IF stub
      ECHO genflow, "red"
    ELSE
      ECHO genflow, "blue"
    FI
    ECHO genflow, "\" style=\"filled\"];\n"
  FI
ENDPROC

PROC LogCall PARMS String caller, String callee ENDPARMS
  IF genflow
    ECHO genflow, "  "
    ECHO genflow, caller
    ECHO genflow, " -> "
    ECHO genflow, callee
    ECHO genflow, ";\n"
  FI
ENDPROC

# foo is a stub
PROC foo PARMS String this, String that ENDPARMS
  LogLabel PROCNAME, TRUE
ENDPROC
# bar is implemented
PROC bar PARMS String this, String that ENDPARMS
  LogLabel PROCNAME, FALSE

  LogCall PROCNAME, "foo"
  foo this, that
  LogCall PROCNAME, "baz"
  baz this, that
ENDPROC
# baz is a stub
PROC baz PARMS String this, String that ENDPARMS
  LogLabel PROCNAME, TRUE
ENDPROC

FUNCTION main PARMS StringList args ENDPARMS
  IF StringList[0] EQCI "-genfuncchart" THEN
    genflow = OPEN "flowchart.dot"
    ECHO genflow, "digraph \"G\" {\n"
    LogLabel "main", FALSE
  ELSE
    genflow = 0
  FI

  LogCall PROCNAME, "foo"  # PROCNAME applies to functions too :-)
  foo stuff, otherstuff

  LogCall PROCNAME, "bar"
  bar whatever, thingy

  ECHO genflow, "};\n"
  CLOSE genflow

  RETURN 0
ENDFUNCTION


In the above pseudocode, the logging code dominates because there's hardly 
any implementation code. In practice, the overhead per function is very low 
(look, for example, at the bodies of foo and baz, where a single line of 
code is sufficient to document the stub).

Just by running the program (with the -genfuncchart option), you generate 
the dot file.

(In fact, I note from the above that my original dot file attempt was a 
little out in terms of the order you'd get, but the principle is sound, I 
think.)

-- 
Richard Heathfield
"Usenet is a strange place" - dmr 29/7/1999
http://www.cpax.org.uk
mail: rjh at above domain

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