On Tue, Sep 6, 2016 at 8:08 PM, Esteban Lorenzano <esteba...@gmail.com> wrote:
> Hi,
>
> sorry for arriving so late to this, but I was on holidays :)
> this is how autoRelease works:
>
> 1) #autoRelease of an object registers object for finalisation with a
> particular executor. Then behaviour is divided:
>
> 2.1.1) for ExternalAddresses, it just registers in regular way, who will call
> #finalize on GC
> 2.1.2) finalize will just call a free assuming ExternalAddress was allocated
> (which is a malloc)
>
> 2.2.1) for all FFIExternalReference, it will register for finalisation what
> #resourceData answers (normally, the handle of the object)
> 2.2.2) finalisation process will call the object
> class>>#finalizeResourceData: method, with the #resourceData result as
> parameter
> 2.2.3) each kind of external reference can decide how to free that data (by
> default is also just freeing).
>
> An example of this is how CairoFontFace works (or AthensCairoSurface).
At the bottom of FFIExternalResourceExecutor class comment I read...
"Note that in #finalizeResourceData: you cannot
access any other properties of your instance,
since it is already garbage collected."
But in my experiments it seems okay to access instance variables in #finalize.
For example...
CXString >> autoRelease
self class finalizationRegistry add: self
CXString >> finalize
Transcript crShow: 'Finalizing CXString ' ; show: self private_flags.
self dispose.
Transcript show: ', done!'.
CXString >>private_flags
"This method was automatically generated"
^handle unsignedLongAt: 5
Libclang getClangVersion autoRelease.
Smalltalk garbageCollect.
"==> Finalizing CXString 1, done! "
Is this an unlucky coincidence? Or maybe something changed from NB
to UFFI? (There is a reference to NB there)
I am wary of believing my results contrary to the comment. That old
engineering principle "When things work, it may be only reinforcing
your misconceptions." :)
cheers -ben
> In you case, you will have something like:
>
> FFIExternalObject subclass: #CXString
>
> CXString class>>#finalizeResourceData: version
> self ffiCall: #(void clang_disposeString(void *version))
>
> notice that here I casted to void*… this is because actually resourceData
> answers a pointer, not the object.
>
> cheers,
> Esteban
