addForeignPtrFinalizer

[Alastair Reid]

> I have to say that, given Simon's patch, I am inclined to revert
> back to the old API for foreign pointers.  

I don't think such a change should be made unless Malcolm and I are
able to implement it.  

I'm not yet convinced that Simon's patch is as easy or correct as it
seems and will not be until it has been heavily tested and until I
have a chance to look carefully at the consequences of the change
elsewhere in the system.  

Also, Malcolm reported using a similar trick but that he couldn't get
it to work reliably (i.e., it was ok if the finalizer did nothing but
call out to C but not otherwise).

> The restriction on pure C land finalizers *is* awkward, and as we
> have already seen implies further changes (ie, adding something like
> `finalizerFree').

We missed a small detail in specifying the change and fixed it when we
went to implement it.  This happens with most design changes and
doesn't seem like evidence of awkwardness to me.


--
Alastair Reid                 alastair at reid-consulting-uk.ltd.uk  
Reid Consulting (UK) Limited  http://www.reid-consulting-uk.ltd.uk/alastair/