Re: lazy evaluation: Goops class/instance customization

[Mikael Djurfeldt]

Maarten Grachten <address@hidden> writes:

> On Wed, 21 May 2003, Mikael Djurfeldt wrote:
>
>> Then, in order to get correct semantics, you should remove
>> `primitive-eval' and instead use the following (untested) version of
>> make-lazy:
>> 
>> (defmacro make-lazy (specification . body)
>>   (let ((attributes (map (lambda (x)      
>>                            (if (keyword? x)
>>                                x
>>                                `(delay ,x)))
>>                          body)))
>>                 `(make ,specification
>>                        ,@attributes)))
>> 
>
> Ah. Indeed, that seems to work as well. But I don't really see where the 
> crucial difference is. 
> (not questioning the superiority of this solution :-)

Try the following code and compare the result for the old and the new
make-lazy:

(define c ()
  (x #:init-keyword #:x #:accessor x)
  #:metaclass <Lazy-Eval-Metaclass>)

(define x 1147)

(define o
        (let ((x 4711))
          (make-lazy c #:x x))

(x o)