[Bf-committers] Question on Rna PROP_POINTER and user counting

[Dalai Felinto]

Thanks Campbell, it worked pretty well. (committed in rev. 29016)

In Blender 2.49 we had an interesting (strange) behaviour. All Logics
that used a pointer (mesh, material, scene, ...) was increasing user
counting when created.
However none of them is doing lib_address_us in readfile.c. Therefore
the user count increase didn't affect anything.

Now at least is more consistent (user count is always the same before
and after you save the file/reopen it). What also means you can delete
the blocks even if they are being used in Logic (it would be nice to
have a warning for that).

Regards,
Dalai
(ps.: sound is the only datablock increasing user counting when
created from Logic. It's been handled correctly in readfile.c (using
_us) but it needs some adjustments. I did a pre-commit today (29021)
but the counting still looks strange.)

2010/5/26 Campbell Barton <ideasman42 at gmail.com>:
> On Wed, May 26, 2010 at 5:31 PM, Dalai Felinto <dfelinto at gmail.com> wrote:
>> I gave it more thought and I think I have solution. I can manually
>> increase/decrease the usercount in a set function of the rna property.
>> It sounds hacky for me and I'm still not even sure it will work (I
>> haven't tried rna setfuncs for pointers).
>>
>> I think a more elegant solution would be to use (fictional name)
>> PROP_POINTER_LINK and have it handled internally. I don't know about
>> the internals though.
>>
>> Regards,
>> Dalai
>>
>> 2010/5/25 Dalai Felinto <dfelinto at gmail.com>:
>>> Hello there,
>>> quick question: Is there a way to have a PROP_POINTER property that
>>> doesn't increase the id user count when "selected"?
>>>
>>> Explanation:
>>> Some times (e.g. BGE Logic TouchSensor) we want to point to a
>>> datablock but don't want to affect its user counting (i.e. stop this
>>> block from being deleted).
>>>
>>> In 2.49 (maybe by design or by bug) we are not increasing user
>>> counting for those in readfile.c (there we are using newlibadr instead
>>> of newlibadr_us). This will give you different usercounting for a
>>> datablock after you re-open it, what is strange. So I was wondering if
>>> is there a way (or it's an acceptable design) to have a Rna Prop
>>> linking to a datablock but without changing it id counting.
>>>
>>> Regards,
>>> Dalai
>>>
>
> At the moment the types themselves define if they get user counts or not.
> This doesnt work when they have user counts in some places and not others.
>
> IIRC Text doesnt have user counts, but Meshes do for eg.
>
> I had to add set functions in 2 places because of this, just make sure
> to add some comment that the only reason they are there is to avoid
> user-counts.
>
> had a look into making the user count work per property and its not
> all that easy (though possible ofcourse)
>
> --
> - Campbell
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