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Re: Tabline function sometimes recalled when highlighting set/changed.

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  • Eric Arnold
    I haven t been idle on this. I was unable to get my test case working for a simple but un-obvious reason. It requires that at least one other window be open.
    Message 1 of 9 , May 1, 2006
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      I haven't been idle on this. I was unable to get my test case working
      for a simple but un-obvious reason. It requires that at least one
      other window be open.

      Run the following, and open two windows. Edit a file in one. Open a
      new line, which I assume triggers the tabline to trigger as the buffer
      becomes modified. Then as you move the cursor around, you should see
      the "Tst#" prompt incrementing with each keystroke.

      let s:counter = 0
      function! Tst()
      call Tst_set_hl()
      let s:counter += 1
      echo 'Tst#'.s:counter
      return 'A test string'
      endfunction

      set tabline=%!Tst()

      if &showtabline < 1
      set showtabline=1 " 2=always
      endif


      function! Tst_set_hl()
      hi! Tst_hl term=bold
      endfunction
    • Bram Moolenaar
      ... I don t see the problem. I have to guess that where you talk about another window you actually mean another tab page, otherwise the tab pages line isn t
      Message 2 of 9 , May 2, 2006
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        Eric Arnold wrote:

        > I haven't been idle on this. I was unable to get my test case working
        > for a simple but un-obvious reason. It requires that at least one
        > other window be open.
        >
        > Run the following, and open two windows. Edit a file in one. Open a
        > new line, which I assume triggers the tabline to trigger as the buffer
        > becomes modified. Then as you move the cursor around, you should see
        > the "Tst#" prompt incrementing with each keystroke.
        >
        > let s:counter = 0
        > function! Tst()
        > call Tst_set_hl()
        > let s:counter += 1
        > echo 'Tst#'.s:counter
        > return 'A test string'
        > endfunction
        >
        > set tabline=%!Tst()
        >
        > if &showtabline < 1
        > set showtabline=1 " 2=always
        > endif
        >
        >
        > function! Tst_set_hl()
        > hi! Tst_hl term=bold
        > endfunction

        I don't see the problem.

        I have to guess that where you talk about another window you actually
        mean another tab page, otherwise the tab pages line isn't displayed at
        all.

        I only see the "Tst#N" displayed when I switch between tab pages with
        "gt".

        I guess your example is missing something essential. Try starting with
        "vim -u NONE".

        --
        "The future's already arrived - it's just not evenly distributed yet."
        -- William Gibson

        /// Bram Moolenaar -- Bram@... -- http://www.Moolenaar.net \\\
        /// sponsor Vim, vote for features -- http://www.Vim.org/sponsor/ \\\
        \\\ download, build and distribute -- http://www.A-A-P.org ///
        \\\ help me help AIDS victims -- http://ICCF-Holland.org ///
      • Benji Fisher
        ... I can reproduce this. As Eric says, it is a little tricky. I wrote the following to test.vim: let s:counter = 0 function! Tst() call Tst_set_hl() let
        Message 3 of 9 , May 2, 2006
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          On Tue, May 02, 2006 at 02:17:58PM +0200, Bram Moolenaar wrote:
          >
          > Eric Arnold wrote:
          >
          > > I haven't been idle on this. I was unable to get my test case working
          > > for a simple but un-obvious reason. It requires that at least one
          > > other window be open.
          > >
          > > Run the following, and open two windows. Edit a file in one. Open a
          > > new line, which I assume triggers the tabline to trigger as the buffer
          > > becomes modified. Then as you move the cursor around, you should see
          > > the "Tst#" prompt incrementing with each keystroke.

          > I don't see the problem.

          I can reproduce this. As Eric says, it is a little tricky. I
          wrote the following to test.vim:

          let s:counter = 0
          function! Tst()
          call Tst_set_hl()
          let s:counter += 1
          echo 'Tst#'.s:counter
          return 'A test string'
          endfunction

          set tabline=%!Tst()

          if &showtabline < 1
          set showtabline=1 " 2=always
          endif


          function! Tst_set_hl()
          hi! Tst_hl term=bold
          endfunction

          Then I started vim with

          $ vim -u test.vim --noplugin test.vim

          (almost as good as -u NONE, right?) It seems that the problem comes up
          (sometimes) when there are two tabs and two windows in one of them:

          :tabnew
          gt
          :sp

          Now, starting from Normal mode, I open a new line and type some
          characters:

          oxxxx

          The message shows up, and the number increases by 2 each time I add a
          character.

          HTH --Benji Fisher
        • Bram Moolenaar
          ... Well, yes, I can see that. What I don t understand is why you expect it not to increase. What happens is that during the redraw of the tabline :hi is
          Message 4 of 9 , May 2, 2006
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            Benji Fisher wrote:

            > On Tue, May 02, 2006 at 02:17:58PM +0200, Bram Moolenaar wrote:
            > >
            > > Eric Arnold wrote:
            > >
            > > > I haven't been idle on this. I was unable to get my test case working
            > > > for a simple but un-obvious reason. It requires that at least one
            > > > other window be open.
            > > >
            > > > Run the following, and open two windows. Edit a file in one. Open a
            > > > new line, which I assume triggers the tabline to trigger as the buffer
            > > > becomes modified. Then as you move the cursor around, you should see
            > > > the "Tst#" prompt incrementing with each keystroke.
            >
            > > I don't see the problem.
            >
            > I can reproduce this. As Eric says, it is a little tricky. I
            > wrote the following to test.vim:
            >
            > let s:counter = 0
            > function! Tst()
            > call Tst_set_hl()
            > let s:counter += 1
            > echo 'Tst#'.s:counter
            > return 'A test string'
            > endfunction
            >
            > set tabline=%!Tst()
            >
            > if &showtabline < 1
            > set showtabline=1 " 2=always
            > endif
            >
            >
            > function! Tst_set_hl()
            > hi! Tst_hl term=bold
            > endfunction
            >
            > Then I started vim with
            >
            > $ vim -u test.vim --noplugin test.vim
            >
            > (almost as good as -u NONE, right?) It seems that the problem comes up
            > (sometimes) when there are two tabs and two windows in one of them:
            >
            > :tabnew
            > gt
            > :sp
            >
            > Now, starting from Normal mode, I open a new line and type some
            > characters:
            >
            > oxxxx
            >
            > The message shows up, and the number increases by 2 each time I add a
            > character.

            Well, yes, I can see that. What I don't understand is why you expect it
            not to increase.

            What happens is that during the redraw of the tabline ":hi" is used,
            which causes a redraw. So 'tabline' is evaluated again and again. You
            must actually be lucky that Vim doesn't hang.

            Just make sure that drawing the tabline doesn't cause Vim to redraw the
            display. In this example you could check if the Tst_hl highlight was
            already set.

            --
            Your company is doomed if your primary product is overhead transparencies.
            (Scott Adams - The Dilbert principle)

            /// Bram Moolenaar -- Bram@... -- http://www.Moolenaar.net \\\
            /// sponsor Vim, vote for features -- http://www.Vim.org/sponsor/ \\\
            \\\ download, build and distribute -- http://www.A-A-P.org ///
            \\\ help me help AIDS victims -- http://ICCF-Holland.org ///
          • Eric Arnold
            ... Two reasons: 1) it doesn t happen in most cases, and 2) because the conditions for the redrawing of the tabline are implicit rather than explicit. It
            Message 5 of 9 , May 2, 2006
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              On 5/2/06, Bram Moolenaar <Bram@...> wrote:
              >
              > Benji Fisher wrote:
              >
              > > On Tue, May 02, 2006 at 02:17:58PM +0200, Bram Moolenaar wrote:
              > > >
              > > > Eric Arnold wrote:
              > > >
              > > > > I haven't been idle on this. I was unable to get my test case working
              > > > > for a simple but un-obvious reason. It requires that at least one
              > > > > other window be open.
              > > > >
              > > > > Run the following, and open two windows. Edit a file in one. Open a
              > > > > new line, which I assume triggers the tabline to trigger as the buffer
              > > > > becomes modified. Then as you move the cursor around, you should see
              > > > > the "Tst#" prompt incrementing with each keystroke.
              > >
              > > > I don't see the problem.
              > >
              > > I can reproduce this. As Eric says, it is a little tricky. I
              > > wrote the following to test.vim:
              > >
              > > let s:counter = 0
              > > function! Tst()
              > > call Tst_set_hl()
              > > let s:counter += 1
              > > echo 'Tst#'.s:counter
              > > return 'A test string'
              > > endfunction
              > >
              > > set tabline=%!Tst()
              > >
              > > if &showtabline < 1
              > > set showtabline=1 " 2=always
              > > endif
              > >
              > >
              > > function! Tst_set_hl()
              > > hi! Tst_hl term=bold
              > > endfunction
              > >
              > > Then I started vim with
              > >
              > > $ vim -u test.vim --noplugin test.vim
              > >
              > > (almost as good as -u NONE, right?) It seems that the problem comes up
              > > (sometimes) when there are two tabs and two windows in one of them:
              > >
              > > :tabnew
              > > gt
              > > :sp
              > >
              > > Now, starting from Normal mode, I open a new line and type some
              > > characters:
              > >
              > > oxxxx
              > >
              > > The message shows up, and the number increases by 2 each time I add a
              > > character.
              >
              > Well, yes, I can see that. What I don't understand is why you expect it
              > not to increase.


              Two reasons: 1) it doesn't happen in most cases, and 2) because the
              conditions for the redrawing of the tabline are implicit rather than
              explicit. It makes sense this would include updating of tabs, etc.
              That highlight commands should cause a redraw which would re-trigger
              the tabline function is not as clear, though in hindsight it does seem
              so.


              > What happens is that during the redraw of the tabline ":hi" is used,
              > which causes a redraw. So 'tabline' is evaluated again and again. You
              > must actually be lucky that Vim doesn't hang.


              Part of what made this so hard to track down was that when I added the
              highlighting call, everything went just fine for a while, and by the
              time I encountered the problem, many other changes had been made to
              the script.

              For reasons I don't understand yet, it requires a very specific set of
              conditions for it to be a problem, which suggests that the loop
              doesn't have to occur at all.


              > Just make sure that drawing the tabline doesn't cause Vim to redraw the
              > display. In this example you could check if the Tst_hl highlight was
              > already set.


              Actually, I must have a recurring highlight reset call in the tabline
              function. It turns out that most anything that resets highlighting
              for a window also clears the highlighting for the tabline, and the
              tabline has no special trigger (i.e. filetype) to tell it to reset its
              highlighting again. I don't see a good way to deal with this other
              than to have a recurring highlighting call in the tabline function.

              As a workaround, I've set a timer which will only allow a highlighting
              reset inside the tabline function every 5 seconds. This works well
              enough, but it does allow a window of failure.
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