[EMAIL PROTECTED] wrote:
Brian Hulley <[EMAIL PROTECTED]> wrote:
My other question is what happens if I want to have a function that
takes more than one ForeignPtr as argument ie
foreign import ccall duma_test :: Ptr (Window a) -> Ptr (Window a)
-> IO ()
test :: ForeignPtr (Window a) -> ForeignPtr (Window a) -> IO ()
test p q = withForeignPtr p (\p' -> withForeignPtr q $ duma_test p')
Is this the only way to achieve this? It seems a bit long-winded and
possibly a bit inefficient...
I use:
\begin{code}
{-# INLINE with2ForeignPtrs #-}
{-# INLINE with3ForeignPtrs #-}
with2ForeignPtrs :: ForeignPtr a -> ForeignPtr b -> (Ptr a -> Ptr b
-> IO c) -> IO c with2ForeignPtrs f1 f2 m = withForeignPtr f1
(withForeignPtr f2 . m) \end{code}
\begin{code}
with3ForeignPtrs :: ForeignPtr a -> ForeignPtr b -> ForeignPtr c ->
(Ptr a -> Ptr b -> Ptr c -> IO d) -> IO d
with3ForeignPtrs f1 f2 f3 m = withForeignPtr f1 (with2ForeignPtrs f2
f3 . m) \end{code}
Good idea!
foreign import ccall duma_init :: IO ()
^^^^
Any relation with duma.sourceforge.net ?
``D.U.M.A. - Detect Unintended Memory Access''
No - I just got it off the cover of a DVD! (after spending about a week
wasting time trying to think of a name... :-) )
Thanks, Brian.
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