When not run in a git repository, git-annex can still display a usage message, and "git annex version" even works.

Things that sound simple, but are made hard by the Annex monad being built
with the assumption that there will always be a git repo.

CmdLine.hs

@@ -11,7 +11,9 @@ module CmdLine (
 	shutdown
 ) where
 
-import System.IO.Error (try)
+import qualified System.IO.Error as IO
+import qualified Control.Exception as E
+import Control.Exception (throw)
 import System.Console.GetOpt
 
 import Common.Annex
@@ -25,14 +27,18 @@ type Params = [String]
 type Flags = [Annex ()]
 
 {- Runs the passed command line. -}
-dispatch :: Params -> [Command] -> [Option] -> String -> Git.Repo -> IO ()
-dispatch args cmds options header gitrepo = do
+dispatch :: Params -> [Command] -> [Option] -> String -> IO Git.Repo -> IO ()
+dispatch args cmds options header getgitrepo = do
 	setupConsole
-	state <- Annex.new gitrepo
-	(actions, state') <- Annex.run state $ do
-		sequence_ flags
-		prepCommand cmd params
-	tryRun state' cmd $ [startup] ++ actions ++ [shutdown]
+	r <- E.try getgitrepo :: IO (Either E.SomeException Git.Repo)
+	case r of
+		Left e -> maybe (throw e) id (cmdnorepo cmd)
+		Right g -> do
+			state <- Annex.new g
+			(actions, state') <- Annex.run state $ do
+				sequence_ flags
+				prepCommand cmd params
+			tryRun state' cmd $ [startup] ++ actions ++ [shutdown]
 	where
 		(flags, cmd, params) = parseCmd args cmds options header
 
@@ -77,7 +83,7 @@ tryRun' errnum _ cmd []
 	| otherwise = return ()
 tryRun' errnum state cmd (a:as) = run >>= handle
 	where
-		run = try $ Annex.run state $ do
+		run = IO.try $ Annex.run state $ do
 			Annex.Queue.flushWhenFull
 			a
 		handle (Left err) = showerr err >> cont False state

Command.hs

@@ -7,6 +7,7 @@
 
 module Command (
 	command,
+	noRepo,
 	next,
 	stop,
 	prepCommand,
@@ -31,9 +32,14 @@ import Logs.Trust
 import Logs.Location
 import Config
 
-{- Generates a command with the common checks. -}
+{- Generates a normal command -}
 command :: String -> String -> [CommandSeek] -> String -> Command
-command = Command commonChecks
+command = Command Nothing commonChecks
+
+{- Adds a fallback action to a command, that will be run if it's used
+ - outside a git repository. -}
+noRepo :: IO () -> Command -> Command
+noRepo a c = c { cmdnorepo = Just a }
 
 {- For start and perform stages to indicate what step to run next. -}
 next :: a -> Annex (Maybe a)

Command/Version.hs

@@ -13,7 +13,7 @@ import qualified Build.SysConfig as SysConfig
 import Annex.Version
 
 def :: [Command]
-def = [dontCheck repoExists $
+def = [noRepo showPackageVersion $ dontCheck repoExists $
 	command "version" paramNothing seek "show version info"]
 
 seek :: [CommandSeek]
@@ -23,7 +23,7 @@ start :: CommandStart
 start = do
 	v <- getVersion
 	liftIO $ do
-		putStrLn $ "git-annex version: " ++ SysConfig.packageversion
+		showPackageVersion
 		putStrLn $ "local repository version: " ++ fromMaybe "unknown" v
 		putStrLn $ "default repository version: " ++ defaultVersion
 		putStrLn $ "supported repository versions: " ++ vs supportedVersions
@@ -31,3 +31,6 @@ start = do
 	stop
 	where
 		vs = join " "
+
+showPackageVersion :: IO ()
+showPackageVersion = putStrLn $ "git-annex version: " ++ SysConfig.packageversion

GitAnnex.hs

@@ -123,4 +123,4 @@ header :: String
 header = "Usage: git-annex command [option ..]"
 
 run :: [String] -> IO ()
-run args = dispatch args cmds options header =<< Git.repoFromCwd
+run args = dispatch args cmds options header Git.repoFromCwd

Logs/Trust.hs

@@ -30,8 +30,8 @@ trustLog = "trust.log"
 trustGet :: TrustLevel -> Annex [UUID]
 trustGet SemiTrusted = do -- special case; trustMap does not contain all these
 	others <- M.keys . M.filter (/= SemiTrusted) <$> trustMap
-	all <- uuidList
-	return $ all \\ others
+	alluuids <- uuidList
+	return $ alluuids \\ others
 trustGet level = M.keys . M.filter (== level) <$> trustMap
 
 {- Read the trustLog into a map, overriding with any

Types/Command.hs

@@ -33,6 +33,7 @@ type CommandCleanup = Annex Bool
 
 {- A command is defined by specifying these things. -}
 data Command = Command {
+	cmdnorepo :: Maybe (IO ()),
 	cmdcheck :: [CommandCheck],
 	cmdname :: String,
 	cmdparams :: String,

debian/changelog

@@ -14,6 +14,8 @@ git-annex (3.20111112) UNRELEASED; urgency=low
     displayed)
   * status: --fast is back
   * Fix support for insteadOf url remapping. Closes: #644278
+  * When not run in a git repository, git-annex can still display a usage
+    message, and "git annex version" even works.
 
  -- Joey Hess <joeyh@debian.org>  Sat, 12 Nov 2011 14:50:21 -0400
 

doc/bugs/git_annex_version_should_without_being_in_a_repo_.mdwn

@@ -3,3 +3,5 @@ was checking the version of git-annex on a machine before cloning a repo...
     $ git annex version
     git-annex: Not in a git repository.
 
+> made difficult by the Annex monad, but I made it work! --[[Joey]]
+> [[done]]

git-annex-shell.hs

@@ -79,8 +79,8 @@ builtins = map cmdname cmds
 builtin :: String -> String -> [String] -> IO ()
 builtin cmd dir params = do
 	checkNotReadOnly cmd
-	Git.repoAbsPath dir >>= Git.repoFromAbsPath >>=
-		dispatch (cmd : filterparams params) cmds options header
+	dispatch (cmd : filterparams params) cmds options header $
+		Git.repoAbsPath dir >>= Git.repoFromAbsPath
 
 external :: [String] -> IO ()
 external params = do