From 1091021c035ba121a66c5dca843ff2b40c7474f4 Mon Sep 17 00:00:00 2001
From: Iustin Pop <iustin@google.com>
Date: Tue, 20 Mar 2012 17:57:33 +0000
Subject: [PATCH] Add two utility functions
These both are work with/on the Result type, so we add them to
BasicTypes. The functions will be used as more generic versions of
some more specialised functions that are right now spread across the
modules.
Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>
---
htools/Ganeti/BasicTypes.hs | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)
diff --git a/htools/Ganeti/BasicTypes.hs b/htools/Ganeti/BasicTypes.hs
index b7b437fa9..fa9e30f77 100644
--- a/htools/Ganeti/BasicTypes.hs
+++ b/htools/Ganeti/BasicTypes.hs
@@ -1,6 +1,6 @@
{-
-Copyright (C) 2009, 2010, 2011 Google Inc.
+Copyright (C) 2009, 2010, 2011, 2012 Google Inc.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
@@ -25,9 +25,13 @@ module Ganeti.BasicTypes
, isBad
, eitherToResult
, annotateResult
+ , annotateIOError
+ , exitIfBad
) where
import Control.Monad
+import System.IO (hPutStrLn, stderr)
+import System.Exit
-- | This is similar to the JSON library Result type - /very/ similar,
-- but we want to use it in multiple places, so we abstract it into a
@@ -71,3 +75,17 @@ eitherToResult (Right v) = Ok v
annotateResult :: String -> Result a -> Result a
annotateResult owner (Bad s) = Bad $ owner ++ ": " ++ s
annotateResult _ v = v
+
+-- | Annotates and transforms IOErrors into a Result type. This can be
+-- used in the error handler argument to 'catch', for example.
+annotateIOError :: String -> IOError -> IO (Result a)
+annotateIOError description exc =
+ return . Bad $ description ++ ": " ++ show exc
+
+-- | Unwraps a 'Result', exiting the program if it is a 'Bad' value,
+-- otherwise returning the actual contained value.
+exitIfBad :: Result a -> IO a
+exitIfBad (Bad s) = do
+ hPutStrLn stderr $ "Failure: " ++ s
+ exitWith (ExitFailure 1)
+exitIfBad (Ok v) = return v
--
GitLab