Re: [Chicken-users] handle "unbound variable" exception for undefined procedures?

[Tobia Conforto]

Shawn Ruledge wrote:
> It would be cool if the proxy method implementations could be  
> defined on an as-needed basis.

IMHO a different object system would be better suited to this "lazy  
method definition".

I'm thinking of a message-passing model (think of Smalltalk or  
Objective-C) where each object is a lambda.  Here is the trivial  
example:

#;1> (define (make-point x y)
--->   (match-lambda*
--->     (('x) x)
--->     (('y) y)
--->     (('x new) (set! x new))
--->     (('y new) (set! y new))))
#;2> (define p1 (make-point 2 3))
#;3> (p1 'x)
2
#;4> (p1 'y 4)
#;5> (p1 'y)
4
#;6>

Mind you, this is the simplest implementation possible, without  
inheritance, polymorphism or anything useful.  But if you find (or  
write) a full-fledged object system that works like this (probably  
based on table lookup instead of static pattern matching) then you  
will have no trouble adding a handler for unknown methods that fetches  
the definitions on the fly.

-Tobia