Re: Handling branch cuts for hypergeometric function s

There are other ways of altering the
ask-integer  program by hacking lisp, but only temporarily.

You can save the old definition and restore it.
e.g.  (setf oldfunction (symbol-function 'ask-integer))..
    ....
       (setf (symbol-function 'ask-integer )oldfunction)

Or (not in Common Lisp, just Scheme)  re-bind the
function definition locally.

Or you can use (in some CL systems)  an "advise" function
that says something like
   when  inside this function change ask-integer to ..... else use
the old definition.

Allegro Common Lisp has this, but also something more general called
fwrapper.

It might also be possible to use object-oriented programming
with inheritance to do something here.  I usually think in terms
of functions, however.

Otherwise, trying to make ask-  smarter seems like a good idea.


RJF


Viktor T. Toth wrote:

.....

> 
> What I am suggesting is a formalized hook function that would be called
> before an ask... function resorts to an interactive query. Something like
> this (please don't take it too literally, this is just pseudocode):
> 
> 	function ask_pred(expression)
> 		if (pred can be evaluated) return result;
> 	+	if (hook_pred is defined)
> 	+		hook_pred(expression);
> 	+		if (pred can now be evaluated) return result;
> 	+	endif
> 		query the user;
> 		return result;
> 	end function
> 
> It is the lines I marked with plus signs that are "new" in the sense that
> they'd have to be added to the existing definitions of the predicate query
> functions if we choose to go in this direction.
> 
> 
> Viktor
> 
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