[PD-dev] [ pure-data-Bugs-1518030 ] GOP subpatch clearing itself crashes Pd

[Mathieu Bouchard]

On Fri, 7 Jul 2006, geiger wrote:

> I think the case should be investigated. A segmentation fault in Pd is a 
> bug and should be avoided.

Yes, and Pd already has several mechanisms for avoiding segfaults, so 
there is precedent. In particular, it has t_gfxstub and t_gpointer, which 
are two kinds of weak pointers. (there is also t_gstub, which is a kind of 
reference-counting pointer, but I'm not sure about categorizing it as a 
"segfault prevention device").

BTW, I have this problem with t_gpointers ... I want to do this,

[gemhead]
  |
[t b a]
  |  |
[list]
  |
[list trim]
  |
[square]

Which a stub in which I'd insert a [until] so as to bang the [list] 
repeatedly. Note that this would all happen before the control is returned 
to [gemhead] (and I'm not destroying the gemwin either), so the gemstate 
message would still be valid. However, [list] wants to copy A_POINTER args 
as t_gpointer structs, whereas all A_POINTERs in GEM/GF/PDP are fake, so i 
get "consistency errors" and I suppose crashes would be possible too. How 
should I deal with this?

BTW someone had an alternate way of doing this using other objects, but I 
don't recall how.

I need this because of [GEMglVertex3f] or whatever the name is.

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| Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju
| Freelance Digital Arts Engineer, Montréal QC Canada