new ForeignPtr without finalizers

[Dean Herington]

On Thu, 12 Jun 2003, Alastair Reid wrote:

> Manuel:
> > In other words, it seem much more likely that one would
> > partially apply `newForeignPtr' to a finaliser than to a
> > pointer that is to be finalised.  But this is a minor point.
> 
> Having written some more ffi code over the last couple of days, I agree that 
> this is much more natural so, even though it will break all the packages I 
> released in the last week, I now vote for swapping the argument order.
> 
> Since this breaks code anyway, we could adopt Dean's proposal to allow lists 
> of arguments to newFP and addFPFinalizers without making things worse.  I 
> don't think we should do this though since I believe they would always be 
> used with singleton or empty arguments and because the list-based versions 
> can be trivially added with a foldM if they prove useful.

Actually, I think I prefer Ashley's idea of separating the creation of a 
ForeignPtr from the addition of a FinalizerPtr.  So how about:

newForeignPtr              :: Ptr a -> IO (ForeignPtr a)
addForeignPtrFinalizer     :: FinalizerPtr a -> ForeignPtr a -> IO ()

newForeignPtrWithFinalizer :: FinalizerPtr a -> Ptr a -> IO (ForeignPtr a)
newForeignPtrWithFinalizer f p = do p' <- newForeignPtr p
                                    addForeignPtrFinalizer f p'
                                    return p'

Dean