Call custom vim completetion menu with Information from Perl-Script - perl

Question

I wrote a script analyzing perl-files (totally without PPI, because it will be used on Servers where the admins don't want PPI to be installed and so on and so forth, but let's not talk about that).
Now, let's say I have this code:
my $object = MySQL->new();
my $ob2 = $object;
$ob2->
(Where MySQL is one of our modules).
My script correctly identifies that $ob2 is a MySQL-Object and sees where it came from, and then returns a list of found subs in that module.
My idea was, that, since I use vim for editing, this could be a really cool way for "CTRL-n"-Completetion.
So, when...
$ob2->[CTRL-n]
It shows the CTRL-n-Box which opens my Perl-Script and gives it a few parameters (I would need: The line that I am actually on, the cursor position and the whole file as it is in vim).
I already found things like vim-perl, which allows me to write something like
if has('perl')
function DefPerl()
perl << EOF
use MyModule;
return call_to_my_function(); # returns all the methods from the object for example
EOF
endfunction
call DefPerl()
endif
But somehow this does not get executed (I tried writing something to a file with a system call just for the sake of testing)...
So, in short:
Does anyone here know how to achieve that? Calling a perl-function from vim by pressing CTRL-n with the full file-code and the line vim is actually in and the position, and then opening a completetion-menu with the results it got from the perl-script?
I hope someone knows what I mean here. Any help would be appreciated.

Answer 1

The details and tips for invoking embedded Perl code from Vim can be found in this Vim Tips Wiki article. Your attempts are already pretty close, but to return stuff from Perl, you need to use Vim's Perl API:
VIM::DoCommand "let retVal=". aMeaningfullThingToReturn
For the completion menu, your Perl code needs to return a List of Vim objects that adhere to the format as described by :help complete-items. And :help complete-functions shows how to trigger the completion. Basically, you define an insert-mode mapping that sets 'completefunc' and then trigger your function via <C-x><C-u>. Here's a skeleton to get your started:
function! ExampleComplete( findstart, base )
if a:findstart
" Locate the start of the keyword.
let l:startCol = searchpos('\k*\%#', 'bn', line('.'))[1]
if l:startCol == 0
let l:startCol = col('.')
endif
return l:startCol - 1 " Return byte index, not column.
else
" Find matches starting with a:base.
let l:matches = [{'word': 'example1'}, {'word': 'example2'}]
" TODO: Invoke your Perl function here, input: a:base, output: l:matches
return l:matches
endif
endfunction
function! ExampleCompleteExpr()
set completefunc=ExampleComplete
return "\<C-x>\<C-u>"
endfunction
inoremap <script> <expr> <Plug>(ExampleComplete) ExampleCompleteExpr()
if ! hasmapto('<Plug>(ExampleComplete)', 'i')
imap <C-x><C-z> <Plug>(ExampleComplete)
endif