[cells-devel] Cells: Controlling the way kids are added to a parent ...

[Frank Goenninger]

Am 31.10.2008 um 00:16 schrieb Kenny Tilton:

> [hmmm... did you get my other response? This is a diff question, but  
> you did not mention my other so I am concenred.]

No, I actually didn't.

> Frank Goenninger wrote:
>> ... and again a question related to this:
>> Suppose I have :
>> (defmd kid-test-2 (family)
>>         (a-slot (c-in nil))
>>         :kids (list (make-instance 'my-kid)
>>                      (make-instance 'my-kid)))
>> Now - this completely bypasses the control mechanism inserted into  
>> fm- kid-add - which is not what I wanted ;-)
>
> Good point, another hole. In ACL and any CL supporting a full MOP,  
> btw, you can supply an around method to (setf slot-value-using- 
> class) which is the implementation of (setf slot-value) and /really/  
> control access. Anyway...
>
>> So, I am asking myself if it would be better to insert the check  
>> into  the .kids observer ...
>
> One big concern I have is, is this too late? Do you have any  
> requirement to stop these sooner? ie, If you want to signal a  
> condition that is fine, but recovering from it means also backing  
> out the change and /that/ would be a lot of work at the late stage  
> when the observer gets called.

Ok. Understood. I will try the s-v-u-c approach ...

Thanks!

Regards,
    Frank
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