[elephant-devel] changing association slots

[LukasGiessmann]

hi,

while we were working on the problem "associations between instances of
the same class" we also were trying to solve the remove-association
problem.

we have a suggestion - it differs a little from the original way, but
maybe it is helpful.

so i sent a patch today.


regards

lukas


> I was getting too much spam so require authentication on the Trac
> now.  The admins can be slow to grant accounts or enable Trac.  If you
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>
> Ian
>
> On Jul 9, 2008, at 3:55 PM, LukasGiessmann wrote:
>
>> Hi Ian,
>>
>> I know this is not the right space to place this question butI don´t
>> know
>> were else I should do it.
>> Tried to get an account for http://trac.common-lisp.net/elephant; I
>> wrote
>> a mail to admin at common-lisp.net but haven´t got an answer yet.
>> Is there another possibility to mark this bug?
>>
>> Best regards
>> Lukas
>>
>>> 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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>>>
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>>
>>
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