How to start search `/` from a mapping?

Question

I'm trying to do the following mapping in my vimrc:

nnoremap <silent> / :call <SID>FooFunction()<CR><BAR>norm! /

But when I press /, instead of running the function and then starting the search prompt, I get this text inserted to my buffer:

rm! /

I also tried to put the normal command to as the last line of FooFunction:

function! s:FooFunction() abort
    ...
    ...
    norm! /
endfunction

but then I don't get any prompt after pressing /.

How can I achieve this?

Answer 1

It seems you've already found a working solution, but I wanted to address the issues with your attempted approaches.

But when I press /, instead of running the function and then starting the search prompt, I get this text inserted to my buffer:

rm! /

You're getting this result because you're using <BAR> in your mapping after you already left command-line mode:

:call <SID>FooFunction()<CR><BAR>norm! /

You're using a <CR>, which means you're back in normal mode, so <BAR>norm! / (or, equivalent, |norm! /) is evaluated as a series of normal mode commands.

Command | moves to a column based on count, without a count, it moves to first column. n repeats the last search. o inserts a new line below the current line and starts insert mode. As you're now in insert mode, the rest of the mapping, rm! /, gets inserted as text.

Removing the <CR> would fix that part of the issue, however that'd be equivalent to your second approach, which doesn't work either, let's take a look:

I also tried to put the normal command to as the last line of FooFunction:

function! s:FooFunction() abort
    ...
    ...
    norm! /
endfunction

but then I don't get any prompt after pressing /.

That's because the norm! command expects to execute a complete command, it doesn't allow for a prompt to be pending at the end of its execution.

From :help :normal:

{commands} should be a complete command. If {commands} does not finish a command, the last one will be aborted as if <Esc> or <C-C> was typed.

So :norm! / doesn't work, the search gets cancelled as the command completes.

An alternative you can use in a function is to call feedkeys(), which doesn't exhibit this behavior. For example, this would have worked:

function! s:FooFunction() abort
    ...
    ...
    call feedkeys('/')
endfunction

But, as you've noticed, an even easier approach is to simply use / directly in your mapping:

nnoremap / :call <SID>FooFunction()<CR>/

Answer 2

Figured out the the <silent> was hiding the search prompt, and also the mapping can be done just like this:

nnoremap / :call <SID>FooFunction()<CR>/