[xmonad] Fwd: Re: Suspend Keybinding Temporarily

30 Nov 2018

      Sorry, i've sent mail privately instead of sending it to the list.

-------- Forwarded Message --------
Subject: Re: [xmonad] Suspend Keybinding Temporarily
Date: Fri, 30 Nov 2018 23:07:01 +0300
From: Dmitriy Matrosov 
To: Brandon Allbery 

On 11/30/2018 12:11 AM, Brandon Allbery wrote:
...
Yes. More specifically, it's ultimately using the execve() syscall, via
one of the wrappers which propagates the environment (which one depends
on whether it's asked to do $PATH search or not).
...
On Thu, Nov 29, 2018 at 4:07 PM Dmitriy Matrosov mailto:sgf.dma@gmail.com> wrote:
On 11/29/2018 09:50 PM, Brandon Allbery wrote:
     > You were talking about restart, between the running xmonad and its
     > replacement via executeFile. There, you can use the environment.
    There
     > is no way to pass information between an invoked "xmonad
    --restart" and
     > the running xmonad.
You mean, `executeFile` preserves environment? So, i may change 
it from
    running xmonad (by e.g. keybinding) and then restart it?
> On Thu, Nov 29, 2018 at 6:01 AM Dmitriy Matrosov
    mailto:sgf.dma@gmail.com
     > mailto:sgf.dma@gmail.com>> wrote:
     >
     >
     >
     >     On November 28, 2018 9:25:00 PM GMT+03:00, Brandon Allbery
     >     mailto:allbery.b@gmail.com
    mailto:allbery.b@gmail.com>> wrote:
     >      >Not by default; there's already a bug (
     >      >https://github.com/xmonad/xmonad/issues/78) about our not
    obeying the
     >      >ICCCM
     >      >replace protocol unless started by replacing some other WM.
     >      >
     >      >There's a few other places you can hide extra parameters;
    starting
     >     that
     >      >early, the environment is probably the easiest to use,
So.. here is version using environment:

         import XMonad
         import XMonad.Operations
         import XMonad.Util.EZConfig

         import System.Environment
         import Control.Exception

         main :: IO ()
         main = do
                 let xcf = def
                             { modMask = mod4Mask
                             , handleExtraArgs = disableKeysE
                             }
                             `additionalKeys`
                             [ ((mod4Mask, xK_d), disableKeysOn) ]
                 xmonad xcf

         disableKeysOn :: X ()
         disableKeysOn       = do
             trace "Preparing to disable keys and restarting.."
             io $ setEnv "XMONAD_DISABLE_KEYS" "1"
             restart "xmonad" True

         disableKeysE :: [String] -> XConfig Layout -> IO (XConfig Layout)
         disableKeysE _ xcf = do
             me <- lookupEnv "XMONAD_DISABLE_KEYS"
             case me of
               Just _    -> do
                 trace "Disabling all keys."
                 unsetEnv "XMONAD_DISABLE_KEYS"
                 return (xcf {keys = \_ -> mempty})
               Nothing   -> return xcf

It also restarts xmonad on key press (when disabling keys) and all
works fine, but.. xmonad frequently crashes with

         xmonad: failed to create OS thread: Resource temporarily 
unavailable

I don't think this crash relates somehow to using environment, and it
happened from time to time before too, but still.. Can you advise,
how to fix it?

provided
...
>     they're
     >      >not
     >      >too large (see why there's a state file now).
     >
     >     Hm, i don't understand how to use environment. I need to pass
     >     something to running xmonad process (to which i send
     >     XMONAD_RESTART). As far as i know, i can't change
environment of
...
>     another process..
     >
     >
     >      >On Wed, Nov 28, 2018 at 1:20 PM Dmitriy Matrosov
     >     mailto:sgf.dma@gmail.com
    mailto:sgf.dma@gmail.com>>
     >      >wrote:
     >      >
     >      >> Hi.
     >      >>
     >      >> On 11/21/2018 09:49 PM, Eyal Erez wrote:
     >      >> > Hi,
     >      >> >
     >      >> > I'm getting some collisions between my xmonad
    keybindings and an
     >      >> > application I'm running (it's a game that is suppose to
    run full
     >      >screen
     >      >> > but in reality just uses a large window).  I was
    wondering if I
     >      >could
     >      >> > suspend or change some keybindings from a script that I
    can run
     >      >before
     >      >> > the app launches and then restore later.
     >      >> >
     >      >> > Is this at all possible?  Happy to entertain other
options.
...
>      >>
     >      >> Here is proof of concept:
     >      >>
     >      >>
     >      >>          import XMonad
     >      >>          import XMonad.Hooks.EwmhDesktops
     >      >>
     >      >>          import System.Directory
     >      >>          import System.FilePath
     >      >>
     >      >>
     >      >>          main :: IO ()
     >      >>          main = do
     >      >>                  let xcf = ewmh $ def
     >      >>                              { modMask = mod4Mask
     >      >>                              , handleExtraArgs =
disableKeys
...
>      >>                              }
     >      >>                  xmonad xcf
     >      >>
     >      >>          disableKeys :: [String] -> XConfig Layout -> IO
    (XConfig
     >      >Layout)
     >      >>          disableKeys _ xcf = do
     >      >>              xd <- getXMonadDir
     >      >>              let disableFn = xd  "disable_keys"
     >      >>              b <- doesFileExist disableFn
     >      >>              if b
     >      >>                then do
     >      >>                  trace "Disabling all keys."
     >      >>                  removeFile disableFn
     >      >>                  return (xcf {keys = \_ -> mempty})
     >      >>                else return xcf
     >      >>
     >      >>
     >      >> To disable all keys create file `~/.xmonad/disable_keys`
    and then
     >      >> restart xmonad with `xmonad --restart`. All keys will be
    disabled
     >      >> _and_ file deleted (to avoid locking yourself), thus next
    restart
     >      >will
     >      >> restore all keys back.
     >      >>
     >      >> As far as i understand, xmonad grabs keys in
    `X.Main.launch` before
     >      >> entering main loop. Thus, the one way to change key grab
    is to
     >      >restart
     >      >> xmonad. I need to modify `XConfig` before calling
     >     X.Main.launch`, and
     >      >> this may be done by `handleExtraArgs` (called in
`launch'` in
...
>      >> `X.Main.xmonad`). Unfortunately, it seems, that xmonad
    does not
     >     allow
     >      >> to pass extra cmd arguments during restart
    (`X.Operations.restart`
     >      >> always starts xmonad with name `xmonad` and no
    arguments). Also, i
     >      >> can't use extensible state in `handleExtraArgs`, because
    it runs in
     >      >> `IO` (`X` context is not yet built at that time).  Thus,
    to pass
     >      >> something to it, i may use either file or (probably)
     >     `--replace`. The
     >      >> above version uses file. And i have no luck with
    `--replace`: it
     >      >> seems, `xmonad` can't replace itself?..
     >      >> _______________________________________________
     >      >> xmonad mailing list
     >      >> xmonad@haskell.org mailto:xmonad@haskell.org
    mailto:xmonad@haskell.org>
     >      >> http://mail.haskell.org/cgi-bin/mailman/listinfo/xmonad
     >      >>
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     >
     >
     >
     > --
     > brandon s allbery kf8nh
     > allbery.b@gmail.com mailto:allbery.b@gmail.com
    mailto:allbery.b@gmail.com>
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--
brandon s allbery kf8nh
allbery.b@gmail.com mailto:allbery.b@gmail.com