vim：map命令，确认键

Question

I've written a few macros in my .vimrc for the version control system I'm using (Perforce) (please don't suggest the perforce plugin for vim, I tried it and I don't like it). They all work fine except the revert macro, which breaks due to a confirmation prompt (which I need so I don't accidentally fat-finger my changes away). It currently looks like this:

map <F8> :if confirm('Revert to original?', "&Yes\n&No", 1)==1 | !p4 revert <C-R>=expand("%:p")<CR><CR><CR>:edit<CR> | endif

This causes bash to complain when vim tries to load the file:

bin/bash: -c: line 0: syntax error near unexpected token `('

Looking at the buffer bash sees, it looks like the error is that vim sends it everything after the first pipe, not just the part meant for bash. I tried a few alternatives but I can't seem to make it work. I've got it to show confirm dialog correctly when I removed the pipes and endif (using shorthand if), but then vim complains after the user gives a response.

Answer 1

I think you want something along these lines:

:map <F8> :if confirm('Revert to original?', "&Yes\n&No", 1)==1 <Bar> exe "!p4 revert" . expand("%:p") <Bar> edit <Bar> endif<CR><CR>

Remember that :map is a dumb sequence of keystrokes: what you're mapping F8 to has to be a sequence of keystrokes that would work if typed. A <CR> in the middle of the :if statement doesn't mean 'and press Enter when executing the command at this point if the condition is true'; it means 'press Enter here when in the middle of typing in the :if command', which obviously isn't what you want.

Building it up a piece at time, from the inside out:

1. There's a shell command you sometimes want to run.
2. That shell command needs to be inside an :if to do the 'sometimes' bit, and so have an :endif following it.
3. After a literal ! everything following is passed to the shell, including | characters which normally signify the start of another Vim command. That's reasonable, because | is a perfectly good character to use in shell commands. So we need some way of containing the shell command. :exe can do this; it executes the supplied string as a command — and its argument, being a string, has a defined end. So the general form is :if condition | exe "!shell command" | endif :if condition | exe "!shell command" | endif :if condition | exe "!shell command" | endif .
4. Your shell command has an expression in it. Using :exe makes this easy, since you can simply concatenate the string constant parts of the command with the result of the expression. So the command becomes :exe "!p4 revert" . expand("%:p") :exe "!p4 revert" . expand("%:p") — try that out on its own on a file, and check it does what you want before going any further.
5. Putting that inside the condition gives you :if confirm('Revert to original?', "&Yes\\n&No", 1)==1 | exe "!p4 revert" . expand("%:p") | edit | endif :if confirm('Revert to original?', "&Yes\\n&No", 1)==1 | exe "!p4 revert" . expand("%:p") | edit | endif :if confirm('Revert to original?', "&Yes\\n&No", 1)==1 | exe "!p4 revert" . expand("%:p") | edit | endif — again try that out before defining the mapping.
6. Once you have that working, define the mapping. A literal | does end a mapping and signify the start of the next Vim command. In your original the mapping definition only went to the end of the condition (check it with :map <F8> after loading a file) and the !p4 part was being run immediately, on the Vim file that defines the mapping! You need to change each | in your command into <Bar> , similarly to how each press of Enter in your command needs writing as <CR> . That gives you the mapping above. Try it by typing it at the command line first, then do :map <F8> again to check it's what you think it is. And only then try pressing F8 .
7. If that works, put the mapping in your .vimrc .

Answer 2

Use of the pipe to string multiple vim commands together is not particularly well-defined, and there are numerous eccentricities. Critically, (see :help :bar ) it can't be used after a command like the shell command :! which sees a | character as its argument.

You might find it easier to use the system() function.

EG

:echo system("p4 revert " . shellescape(expand("%:p")))

The shellescape() wrapper is useful in case you have characters like spaces or quotes in the filename (or have cleverly named it ; rm -rf ~ (Don't try this at home!)).

In the interest of creating more readable/maintainable code, you may want to move your code into a function:

function Revert()
    if confirm('Revert to original?', "&Yes\n&No", 1)==1
        return system("p4 revert " . shellescape(expand("%:p")))
    endif
endfunction

which you would access by using the :call or :echo command in your macro.