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|
{-# LANGUAGE DeriveDataTypeable #-}
-----------------------------------------------------------------------------
-- |
-- Module : XMonad.Util.SpawnNamedPipe
-- Copyright : (c) Christian Wills 2014
-- License : BSD3-style (see LICENSE)
--
-- Maintainer : cwills.dev@gmail.com
-- Stability : unstable
-- Portability : not portable
--
-- A module for spawning a pipe whose "Handle" lives in the Xmonad state.
--
-----------------------------------------------------------------------------
module XMonad.Util.SpawnNamedPipe (
-- * Usage
-- $usage
spawnNamedPipe
, getNamedPipe
) where
import XMonad
import XMonad.Util.Run
import System.IO
import qualified XMonad.Util.ExtensibleState as XS
import Control.Monad
import qualified Data.Map.Strict as Map
-- $usage
-- This module makes it possible to spawn a pipe to Dzen2 in the startupHook
-- and write to it from inside the logHook without the need for global
-- variables.
--
-- > import XMonad.Util.SpawnNamedPipe
-- > import Data.Maybe
-- >
-- > -- StartupHook
-- > startupHook' = spawnNamedPipe "dzen2" "dzenPipe"
-- >
-- > -- LogHook
-- > logHook' = do
-- > mh <- getNamedPipeHandle "dzenPipe"
-- > dynamicLogWithPP $ defaultPP {
-- > ppOutput = maybe (\s -> return ()) (hPutStrLn) mh}
-- >
-- > -- Main
-- > main = xmonad $ defaultConfig {
-- > startupHook = startupHook'
-- > , logHook = logHook'}
--
data NamedPipes = NamedPipes { pipeMap :: Map.Map String Handle }
deriving (Show, Typeable)
instance ExtensionClass NamedPipes where
initialValue = NamedPipes Map.empty
-- | When 'spawnNamedPipe' is executed with a command "String" and a name
-- "String" respectively. The command string is spawned with 'spawnPipe' (as
-- long as the name chosen hasn't been used already) and the "Handle" returned
-- is saved in Xmonad's state associated with the name "String".
spawnNamedPipe :: String -> String -> X ()
spawnNamedPipe cmd name = do
b <- XS.gets (Map.member name . pipeMap)
unless b $ do
h <- spawnPipe cmd
XS.modify (NamedPipes . Map.insert name h . pipeMap)
-- | Attempts to retrieve a "Handle" to a pipe previously stored in Xmonad's
-- state associated with the given string via a call to 'spawnNamedPipe'. If the
-- given string doesn't exist in the map stored in Xmonad's state Nothing is
-- returned.
getNamedPipe :: String -> X (Maybe Handle)
getNamedPipe name = XS.gets (Map.lookup name . pipeMap)
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