[elephant-devel] changing association slots

[Ian Eslick]

I haven't looked at that code in a bit, but I suspect that the right  
thing happens if you just remove the association definition from  
defclass and reevaluate the defclass form.  Can you mark this as a bug  
in elephant so I can remember to look into it later?

Thank you,
Ian

On Jul 4, 2008, at 4:24 AM, LukasGiessmann wrote:

> hello,
>
> since our last mail working with associations turned out to go quite  
> well
> but one more problem came up:
> i tried to change the associations by removing it and replacing it  
> by a
> new association. but the function "remove-association" only works
> partially.
>
> 1. in this one-to-one association the function doesn't work at all.
> ---
> (defpclass job()
>  ((title :initarg :title :accessor title-of :index t)
>   (company :initarg :company :accessor company-of :index t)
>   (job-holder :initarg :job-holder :accessor job-holder-of :associate
> person)))
>
> (defpclass person()
>  ((name :initarg :name :accessor name-of :index t)
>   (job :initarg :job :accessor job-of :associate job)))
> ---
>
> an error message shows up:
>
> (remove-association *job1* 'job-holder *person1*) ; -> There is no
> applicable method for the generic function  #<STANDARD-GENERIC- 
> FUNCTION
> ELEPHANT::OID (1)> when called with arguments (NIL).
>
> same thing happens when i use the following statement:
> (setf (job-holder-of *job1*) nil)
>
>
> 2. by one-to-many associations generally nothing happens at all.
> ---
> (defpclass job()
>  ((title :initarg :title :accessor title-of :index t)
>   (company :initarg :company :accessor company-of :index t)
>   (job-holders :accessor job-holders-of :associate (person job))))
>
> (defpclass person()
>  ((name :initarg :name :accessor name-of :index t)
>   (job :initarg :job :accessor job-of :associate job)))
> ---
>
> it only works in this case:
> ---
> (drop-instance *person2*)
> (remove-association *job2* 'job-holders *person2*)
> ---
>
>
> 3. in the case of many-to-many associations everything goes fine.
>
> how do i get the "remove-association" function to work?
> are there other ways for changing associations?
>
>
> thank you for your help
>
> lukas
>
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