[Haskell-cafe] getting data through foreign layer without
florbitous at gmail.com
Mon Dec 14 02:21:10 EST 2009
2009/12/14 Donn Cave <donn at avvanta.com>:
> I'm working with a C++ application library, of the sort where
> you instantiate a subclass of the library object and it dispatches
> your functions on receipt of various events. With multiple OS
> threads, by the way.
> This works all right so far, with some C++ boilerplate and Haskell
> FunPtrs created via the foreign "wrapper" option, but I am not crazy
> about marshalling the application data, to get it to the C++ object
> and back to my application functions.
> So, I'm wondering if the way I'm trying to thread application data
> through the C++ layer is reasonably fool-proof - I mean, empirically
> it works in a simple test, but are there going to be storage issues,
> etc.? Is there a better way to do it?
> - my callbacks
> AppData -> CPlusObjectPtr -> P0 ... -> IO Pn
> - the FunPtr inserted into C++ object
> FunPtr (CPlusObjectPtr -> P0 ... -> IO Pn)
> ... i.e, I apply the AppData parameter first
> - I rewrite the C++ object's FunPtrs every time I update the
> application data (freeHaskellFunPtr prior values.)
> I'm just not sure where AppData lives while it's referenced in a
> FunPtr via partial application, if there might be multiple copies, etc.
I don't fully understand what you want to do, but perhaps you can use
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