CmdLineEnter, CmdLineLeave are triggered from mappings

[justinmk]

Actual behavior:

:au CmdLineEnter * echom localtime()
:nnoremap a :<CR>

Then typing a will trigger the CmdLineEnter handler.

Expected behavior:

Given that CmdLineEnter, CmdLineLeave are mostly for interactive use-cases, it seems like an oversight to also invoke them from mappings. Also based on :help CmdLineEnter.

Could check KeyTyped:

diff --git a/src/ex_getln.c b/src/ex_getln.c
index 0124098da519..7a7e4537bfbd 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -418,7 +418,8 @@ getcmdline(
 
     /* Trigger CmdlineEnter autocommands. */
     cmdline_type = firstc == NUL ? '-' : firstc;
-    trigger_cmd_autocmd(cmdline_type, EVENT_CMDLINEENTER);
+    if (KeyTyped)
+       trigger_cmd_autocmd(cmdline_type, EVENT_CMDLINEENTER);
 
 #ifdef FEAT_CMDHIST
     init_history();
@@ -1957,7 +1958,8 @@ cmdline_not_changed:
 
 cmdline_changed:
        /* Trigger CmdlineChanged autocommands. */
-       trigger_cmd_autocmd(cmdline_type, EVENT_CMDLINECHANGED);
+       if (KeyTyped)
+           trigger_cmd_autocmd(cmdline_type, EVENT_CMDLINECHANGED);
 
 #ifdef FEAT_SEARCH_EXTRA
        /*
@@ -2158,7 +2160,8 @@ returncmd:
        need_wait_return = FALSE;
     
     /* Trigger CmdlineLeave autocommands. */
-    trigger_cmd_autocmd(cmdline_type, EVENT_CMDLINELEAVE);
+    if (KeyTyped)
+       trigger_cmd_autocmd(cmdline_type, EVENT_CMDLINELEAVE);
 
     State = save_State;
 #ifdef HAVE_INPUT_METHOD

[andymass]

What if the user has a map like nnoremap \b :b<space>? Would/should the autocmd be triggered?

[brammool]

Justin M Keyes wrote:

# Actual behavior: ``` :au CmdLineEnter * echom localtime() :nnoremap a :<CR> ``` Then typing `a` will trigger the CmdLineEnter handler. # Expected behavior: Given that CmdLineEnter, CmdLineLeave are mostly for interactive use-cases, it seems like an oversight to also invoke them from mappings. Also based on `:help CmdLineEnter`. Could check `KeyTyped`:

That becomes too unpredictable. Users may map some keys, use them as shortcuts. However, when the whole command is generated, the user is never prompted to type anything, I suppose the autocommands are not useful. So perhaps triggering could be postponed until waiting for a character to be typed? Not sure what the actual problem is we are trying to fix here.

…

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[justinmk]

Not sure what the actual problem is we are trying to fix here.

It's a potential performance problem: : in maps will trigger CmdLineEnter for no reason. As I said, my assumption (and :help CmdLineEnter) is that CmdLineEnter is for interactive use-cases, so triggering it in mappings will make many mappings slow which previously were not.

However, I just noticed that InsertCharPre works the same way.

:au InsertCharPre * echom localtime()
:nnoremap a ifoo<esc>
a

I'll leave it up to discussion whether to close this.

[markonm]

So perhaps triggering could be postponed until waiting for a character to be typed?

+1. I would like that change.

What would happen if mapping exits command line immediately without waiting for typed character? Would CmdLineEnter event be skipped? What about CmdLineLeave, would it also be skipped? If user calls command line window via q:, CmdwinEnter event would be emitted before CmdlineEnter, that would mess up order of events.

Events can already be postponed until waiting for a character with the help of timers.

function! s:do_domething() abort
  echom localtime()
endfunction
au vimrc CmdlineEnter : let s:do = timer_start(0, {-> s:do_domething()})
au vimrc CmdlineLeave : call timer_stop(s:do)

[justinmk]

Events can already be postponed until waiting for a character with the help of timers.

That doesn't solve the problem at all, it just creates more problems for plugin authors. If timers were a solution we wouldn't have needed CmdLineEnter in the first place.

[brammool]

> Not sure what the actual problem is we are trying to fix here. If you have an autocmd which temporarily enables `'relativenumber'` while you're on the command-line, maybe to help you write a range: augroup my_cmdline autocmd! autocmd CmdlineEnter : setlocal relativenumber number | redraw autocmd CmdlineLeave : setlocal norelativenumber nonumber augroup END It may be triggered when the command-line is entered from a mapping or an autocmd, which is distracting if you disable `'relativenumber'` by default. Because it makes the column number appear and disappear immediately afterwards, when you don't expect it (i.e. press a mapping which executes an Ex command for example). It sometimes does on my machine if I install the previous autocmd, but I don't know exactly which mappings or other autocmds are interacting. > So perhaps triggering could be postponed until waiting for a character to be typed? +1. I would like that change.

For your example it would work well to postpone CmdlineEnter until starting to wait for a character. I assume CmdlineChanged would only be triggered after CmdlineEnter. Although these changes seem like a good idea, I wonder if anything would break. Some plugin that depends on the autocmd events even when the user is not typing the cmdline?

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[mg979]

I was trying to use this autocmd to check if the user left the command line without typing anything.
Maybe the autocmd could be activated on demand via set something? So you would do, for example:

set cmdlineau

and somewhere else:

au CmdlineLeave * call func() | set nocmdlineau

and the event wouldn't trigger at all if the setting is off.

[lacygoill]

Now that we have the pseudo-key <cmd> (since 8.2.1978), I think the issue can be closed. If we want the Cmdline* events to be fired, we can enter the command-line with :. If we don't want them to be fired, we can enter the command-line with <cmd>.