Redefining structure accessors (summary)

[Helmut Eller]

* Raymond Toy [2010-03-17 04:57+0100] writes:

> On 3/16/10 6:06 PM, Helmut Eller wrote:
>> * Raymond Toy [2010-03-16 21:48+0100] writes:
>>
>>   
>>> Actually, there's one other alternative.   When the accessor is
>>> redefined, we can silently (or noisily) replace the dsd-accessor
>>> function with nil.  Then we don't get the strange behavior of our
>>> redefined function being used to access the slot.   This also means we
>>> can't actually access the slot ourselves either because we'll try to get
>>> the fdefinition of nil.  But the structure and everything else remains
>>> defined.
>>>
>>> (I have not tried that out yet.)
>>>     
>> If it works, good.
>>   
> Seems to work.  But perhaps this is overly complex.  Maybe we should
> just give up.  We can signal a continuable error and if the user really
> wants to redefine the accessor, let him.  It's up to him to make sure
> it's still usable as an accessor.  If not, that's his problem; we warned
> him. :-)

Yes, right.  There might also be a problem with PCL which seems to
create mirror classes (in a too hairy to understand fashion) and may or
may not keep it's own copy of dsd-accessor.  Either way
structure-slotd-reader-function in pcl/low.lisp looks suspicious.

Helmut