In a recent discussion with Manuel Chakravarty the following question
arose. Given the following code:
foo = do
ba <- newMutableByteArray ...
...
bar ba
-- ba not used here anymore
foreign import ... bar :: MutableByteArray ... -> IO ()
Let's further assume that bar makes callbacks to Haskell-land where a
GC occurs. Now the subtle question: Is it *guaranteed* that ba is
considered alive until bar returns or not? Either way, this should be
clarified in the FFI documentation.
Background: A lot of APIs (e.g. GTK+ and OpenGL :-) have functions
expecting a pointer to some data. One possible way to use them from
Haskell is
* malloc area
* fill area with data
* call API function with pointer to area
* explicitly free malloced area
Using (Mutable)ByteArrays would simplify thing here, especially the
last step would not be needed.
Cheers,
Sven
--
Sven Panne Tel.: +49/89/2178-2235
LMU, Institut fuer Informatik FAX : +49/89/2178-2211
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mailto:[EMAIL PROTECTED] D-80538 Muenchen
http://www.informatik.uni-muenchen.de/~Sven.Panne
