Cabal rebuilding all of the C++ code for wxHaskell
Hi all, I've been trying to resolve a compile time issue[1] with wxHaskell, and I thought I'd throw it open to see if anyone on cafe can help. Here's the crux of the issue: The Setup.hs for wxcore (the major component of wxHaskell) uses "simpleUserHooks", overriding only "confHook". However there is also "cleanHook", which is defined by simpleUserHooks to be: cleanHook = \p _ _ f -> clean p f, If you consult the source for clean[2] you'll see that it tries to "remove the whole dist/ directory rather than tracking exactly what files we created in there". I presume that's why we have to do a full re-build every time? To try and circumvent this I modified the definition of "main" in Setup.hs to this: main = defaultMainWithHooks simpleUserHooks { confHook = myConfHook, cleanHook = (\_ _ _ _ -> return ())} Unfortunately it still seems to re-build all the C++ on each 'install' from cabal. Not sure why? Dave, [1] http://sourceforge.net/mailarchive/message.php?msg_id=28099997 [2] Taken from http://www.haskell.org/ghc/docs/6.10.4/html/libraries/Cabal/src/Distribution... -- Cleaning clean :: PackageDescription -> CleanFlags -> IO () clean pkg_descr flags = do let distPref = fromFlag $ cleanDistPref flags notice verbosity "cleaning..." maybeConfig <- if fromFlag (cleanSaveConf flags) then maybeGetPersistBuildConfig distPref else return Nothing -- remove the whole dist/ directory rather than tracking exactly what files -- we created in there. chattyTry "removing dist/" $ do exists <- doesDirectoryExist distPref when exists (removeDirectoryRecursive distPref) -- these live in the top level dir so must be removed separately removeRegScripts -- Any extra files the user wants to remove mapM_ removeFileOrDirectory (extraTmpFiles pkg_descr) -- If the user wanted to save the config, write it back maybe (return ()) (writePersistBuildConfig distPref) maybeConfig where removeFileOrDirectory :: FilePath -> IO () removeFileOrDirectory fname = do isDir <- doesDirectoryExist fname isFile <- doesFileExist fname if isDir then removeDirectoryRecursive fname else if isFile then removeFile fname else return () verbosity = fromFlag (cleanVerbosity flags)
On Thu, Sep 29, 2011 at 7:15 PM, DukeDave
Hi all, I've been trying to resolve a compile time issue[1] with wxHaskell, and I thought I'd throw it open to see if anyone on cafe can help. Here's the crux of the issue:
The Setup.hs for wxcore (the major component of wxHaskell) uses "simpleUserHooks", overriding only "confHook". However there is also "cleanHook", which is defined by simpleUserHooks to be: cleanHook = \p _ _ f -> clean p f,
If you consult the source for clean[2] you'll see that it tries to "remove the whole dist/ directory rather than tracking exactly what files we created in there". I presume that's why we have to do a full re-build every time?
To try and circumvent this I modified the definition of "main" in Setup.hs to this:
Why do you want to change the behavior of the 'clean' hook? Most users would expect it to clear out everything that 'configure', 'build' and such have done. I would be cautious about subverting user expectations like that. Antoine
On Friday, 30 September 2011 01:42:00 UTC+1, Antoine Latter wrote:
Why do you want to change the behavior of the 'clean' hook? Most users would expect it to clear out everything that 'configure', 'build' and such have done.
I would be cautious about subverting user expectations like that.
I'm only inquiring about changing the clean hook for this specific project, not cabal in general. And the reason I'm looking to change it is that building the C++ component takes a long time (over five minutes on my fairly average laptop), so cleaning everything every time is an extremely annoying inconvenience. My main questions are: 1. Is there some reason (other than 'safety') that "cabal install" cleans everything up? 2. Why does setting cleanHook to return () not have any effect? Thanks,
On 30/09/11 02:45, DukeDave wrote:
1. Is there some reason (other than 'safety') that "cabal install" cleans everything up?
As far as I've experienced and understand it, it doesn't - it's more that GHC can detect when Haskell modules don't need recompiling while the same is not true for C or C++ sources. For example, I change one module and see GHC report only that module and its dependents being recompiled, while the other compiled modules are reused from previous 'cabal install' runs. The "C-sources:" are recompiled every time even if unchanged, which I too find it somewhat annoying even with my small projects.
2. Why does setting cleanHook to return () not have any effect?
I think becausae the clean hook is probably not called by 'cabal install', but by 'cabal clean'. Claude
On 30 September 2011 03:02, Claude Heiland-Allen
On 30/09/11 02:45, DukeDave wrote:
1. Is there some reason (other than 'safety') that "cabal install" cleans everything up?
As far as I've experienced and understand it, it doesn't - it's more that GHC can detect when Haskell modules don't need recompiling while the same is not true for C or C++ sources. For example, I change one module and see GHC report only that module and its dependents being recompiled, while the other compiled modules are reused from previous 'cabal install' runs. The "C-sources:" are recompiled every time even if unchanged, which I too find it somewhat annoying even with my small projects.
Excellent, that is consistent with what I'm seeing, and I'm glad I'm not the only one who finds it annoying. I have no familiarity with how cabal and GHC handle C-sources, but I presume that the job of building them is handed off to a local C/C++ compiler (I presume g++ in my case). Given this I can only assume that cabal is doing something: 1. Deleting the object files before calling the C compiler (and so everything must be rebuilt)? 2. Touching the source C files in some way, before calling the C compiler? 3. Passing some argument to the compiler which is telling it to rebuild everything? 4. Something else?
2. Why does setting cleanHook to return () not have any effect?
I think becausae the clean hook is probably not called by 'cabal install', but by 'cabal clean'.
Ah yes, that does make sense, my bad.
Claude
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participants (4)
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Antoine Latter -
Claude Heiland-Allen -
Dave Tapley -
DukeDave