On Wed, Sep 25, 2002 at 09:33:04AM +0100, Ross Paterson wrote:
If the struct were allocated with mallocForeignPtr, you need another C call to use as the finalizer for that, say hs_f_free().
Sorry, that's wrong: If the struct were allocated with mallocForeignPtr, you're stuck. You've no choice but to use addForeignPtrFinalizer, except that you can't because the order of finalizers is unspecified.
I can guarantee in GHC that if you add a finalizer to a ForeignPtr made with mallocForeignPtr, then it will run before the memory is released. However, to provide a general ordering property on finalizers would be quite awkward in GHC - I just can't think of an easy way to do it. One way is to add a unique tag to each weak pointer object and sort them before running the finalizers, but also the finalizers have to run sequentially somehow (currently there's a hack to run some finalizers in the same thread, but it's nothing more than a performance hack; I don't think I could use it to provide reliable ordering). I tell you what, I'll implement finalizer ordering if you guys implement full Haskell finalizers :-) Cheers, Simon