From 847944e6b13515582d3d55cd0b394f008da2b3b7 Mon Sep 17 00:00:00 2001
From: Joey Hess <joeyh@joeyh.name>
Date: Wed, 20 Jul 2016 14:03:54 -0400
Subject: [PATCH] more generic showStart'

---
 Command/DropKey.hs       |  2 +-
 Command/SetPresentKey.hs |  2 +-
 Messages.hs              | 28 ++++++++++++++++++++++++----
 3 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/Command/DropKey.hs b/Command/DropKey.hs
index 15d5403a8f..9a9d513543 100644
--- a/Command/DropKey.hs
+++ b/Command/DropKey.hs
@@ -42,7 +42,7 @@ seek o = do
 
 start :: Key -> CommandStart
 start key = do
-	showStart' "dropkey" key Nothing
+	showStart' "dropkey" key key
 	next $ perform key
 
 perform :: Key -> CommandPerform
diff --git a/Command/SetPresentKey.hs b/Command/SetPresentKey.hs
index 35ede9553a..73847792da 100644
--- a/Command/SetPresentKey.hs
+++ b/Command/SetPresentKey.hs
@@ -23,7 +23,7 @@ seek = withWords start
 
 start :: [String] -> CommandStart
 start (ks:us:vs:[]) = do
-	showStart' "setpresentkey" k Nothing
+	showStart' "setpresentkey" k k
 	next $ perform k (toUUID us) s
   where
 	k = fromMaybe (error "bad key") (file2key ks)
diff --git a/Messages.hs b/Messages.hs
index 57541cfc05..6851729aec 100644
--- a/Messages.hs
+++ b/Messages.hs
@@ -1,10 +1,12 @@
 {- git-annex output messages
  -
- - Copyright 2010-2014 Joey Hess <id@joeyh.name>
+ - Copyright 2010-2016 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU GPL version 3 or higher.
  -}
 
+{-# LANGUAGE TypeSynonymInstances, FlexibleInstances #-}
+
 module Messages (
 	showStart,
 	showStart',
@@ -57,9 +59,27 @@ showStart :: String -> FilePath -> Annex ()
 showStart command file = outputMessage (JSON.start command (Just file) Nothing) $
 	command ++ " " ++ file ++ " "
 
-showStart' :: String -> Key -> Maybe FilePath -> Annex ()
-showStart' command key afile = outputMessage (JSON.start command afile (Just key)) $
-	command ++ " " ++ fromMaybe (key2file key) afile ++ " "
+class ActionItem i where
+	actionItemDesc :: i -> Key -> String
+	actionItemWorkTreeFile :: i -> Maybe FilePath
+
+instance ActionItem FilePath where
+	actionItemDesc f _ = f
+	actionItemWorkTreeFile = Just
+
+instance ActionItem AssociatedFile where
+	actionItemDesc (Just f) _ = f
+	actionItemDesc Nothing k = key2file k
+	actionItemWorkTreeFile = id
+
+instance ActionItem Key where
+	actionItemDesc k _ = key2file k
+	actionItemWorkTreeFile _ = Nothing
+
+showStart' :: ActionItem i => String -> Key -> i -> Annex ()
+showStart' command key i = 
+	outputMessage (JSON.start command (actionItemWorkTreeFile i) (Just key)) $
+		command ++ " " ++ actionItemDesc i key ++ " "
 
 showNote :: String -> Annex ()
 showNote s = outputMessage (JSON.note s) $ "(" ++ s ++ ") "