#5091: Proposal: Retrieving the System Event Manager
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Reporter: basvandijk | Owner:
Type: task | Status: new
Priority: normal | Component: libraries/base
Version: 7.0.3 | Keywords:
Testcase: | Blockedby:
Os: Unknown/Multiple | Blocking:
Architecture: Unknown/Multiple | Failure: None/Unknown
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When you want to use the system event manager (the one started by the
RTS) you currently have to do something like this:
{{{
{-# LANGUAGE ForeignFunctionInterface #-}
import System.Event (EventManager)
import GHC.Conc.Sync (sharedCAF)
import Foreign.Ptr (Ptr)
import Data.IORef (IORef, newIORef, readIORef)
import System.IO.Unsafe (unsafePerformIO)
main = do
Just mgr <- readIORef eventManager
...
eventManager :: IORef (Maybe EventManager)
eventManager = unsafePerformIO $ do
em <- newIORef Nothing
sharedCAF em getOrSetSystemEventThreadEventManagerStore
{-# NOINLINE eventManager #-}
foreign import ccall unsafe "getOrSetSystemEventThreadEventManagerStore"
getOrSetSystemEventThreadEventManagerStore :: Ptr a -> IO (Ptr a)
}}}
I propose to abstract this ugliness in a function:
{{{
getSystemEventManager :: IO (Maybe EventManager)
getSystemEventManager = readIORef eventManager
}}}
and export it from `GHC.Event`.
I don't think this needs to go through the library submission process
since the module is GHC specific.
See the [http://thread.gmane.org/gmane.comp.lang.haskell.libraries/15458/
thread on the libraries list].
--
Ticket URL: <http://hackage.haskell.org/trac/ghc/ticket/5091>
GHC <http://www.haskell.org/ghc/>
The Glasgow Haskell Compiler
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