2009/12/14 Donn Cave <d...@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? > > Briefly, > - 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 a StablePtr: http://www.haskell.org/ghc/docs/latest/html/libraries/base/Foreign-StablePtr.html Cheers, Bernie. _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
