closes #142

ihaskell-display/ihaskell-charts/IHaskell/Display/Charts.hs

@@ -30,9 +30,7 @@ instance IHaskellDisplay (Renderable a) where
 
 chartData :: Renderable a -> FileFormat -> IO DisplayData
 chartData renderable format = do
-  -- Switch to a temporary directory so that any files we create aren't
-  -- visible. On Unix, this is usually /tmp.
-  try (getTemporaryDirectory >>= setCurrentDirectory) :: IO (Either SomeException ())
+  switchToTmpDir
 
   -- Write the PNG image.
   let filename = ".ihaskell-chart.png"

ihaskell-display/ihaskell-diagrams/IHaskell/Display/Diagrams.hs

@@ -20,9 +20,7 @@ instance IHaskellDisplay (Diagram Cairo R2) where
 
 diagramData :: Diagram Cairo R2 -> OutputType -> IO DisplayData
 diagramData renderable format = do
-  -- Switch to a temporary directory so that any files we create aren't
-  -- visible. On Unix, this is usually /tmp.
-  try (getTemporaryDirectory >>= setCurrentDirectory) :: IO (Either SomeException ())
+  switchToTmpDir
 
   -- Compute width and height.
   let w = width renderable

ihaskell-display/ihaskell-juicypixels/IHaskell/Display/Juicypixels.hs

@@ -29,9 +29,8 @@ instance IHaskellDisplay (Image PixelCMYK16) where display = displayImageAsJpg .
 -- main rendering function
 displayImageAsJpg ::  DynamicImage -> IO Display
 displayImageAsJpg renderable = do
-  -- Switch to a temporary directory so that any files we create aren't
-  -- visible. On Unix, this is usually /tmp.
-  try (getTemporaryDirectory >>= setCurrentDirectory) :: IO (Either SomeException ())
+  switchToTmpDir
+
   let filename = ".ihaskell.juicypixels.jpg"
   -- Write the image
   saveJpgImage 95 filename renderable

ihaskell.cabal

@@ -91,7 +91,8 @@ library
                        stm                  -any,
                        text                 -any,
                        utf8-string          -any,
-                       vector               -any
+                       vector               -any,
+                       temporary            ==1.2.*
 
   exposed-modules: IHaskell.Display
                    IHaskell.Convert

src/IHaskell/Display.hs

@@ -9,6 +9,7 @@ module IHaskell.Display (
   Display(..),
   DisplayData(..),
   printDisplay,
+  switchToTmpDir,
 
   -- Internal only use
   displayFromChan,
@@ -23,6 +24,10 @@ import qualified Data.ByteString.Base64 as Base64
 import qualified Data.ByteString.Char8 as Char
 import Data.Aeson (Value)
 
+import System.Directory(getTemporaryDirectory, setCurrentDirectory)
+import System.IO.Temp(createTempDirectory)
+
+
 import Control.Concurrent.STM.TChan
 import System.IO.Unsafe (unsafePerformIO)
 
@@ -122,3 +127,14 @@ unfoldM f = maybe (return []) (\r -> (r:) <$> unfoldM f) =<< f
 -- notebook once the current execution call ends.
 printDisplay :: IHaskellDisplay a => a -> IO ()
 printDisplay disp = display disp >>= atomically . writeTChan displayChan
+
+-- | Convenience function for client libraries. Switch to a temporary
+-- directory so that any files we create aren't visible. On Unix, this is
+-- usually /tmp.
+switchToTmpDir = void (try switchDir :: IO (Either SomeException ()))
+  where 
+    switchDir =
+      getTemporaryDirectory  >>=
+      flip createTempDirectory "ihaskell-display-tmp" >>=
+      setCurrentDirectory
+