The target is to have the key j doing a possibly complex task and moving to the next line (the latter action performed just like the original function of the j key).
My initial attempt was to map j key this way:
nn j :<C-U>execute "call MyFun(" . v:count . ")"<CR>
(as you can see I intend to make j's behavior depend on the count which is prepended to it)
and to define the function MyFun appropriately:
fu! MyFun(count)
" do more stuff based on a:count
normal j
endf
which is faulty, as hitting j now results in the error E169: Command too recursive, since the non-recursivity of nnoremap, as long as my deduction is correct, applies to the "literal" content of the {rhs} of the mapping, and not to whatever is "inside" it (in other words the function body makes use of the meaning of j at the moment it is called, thus causing the infinte recursion).
Therefore I tried the following
nn , j
nn j :<C-U>execute "call MyFun(" . v:count . ")"<CR>
fu! MyFun(count)
" do more stuff based on a:count
normal ,
endf
However this means that I waste the key ,. I know I can avoid the waste of that mapping doing
nn <Plug>Nobody j
but then I wouldn't know how to use <Plug>Nobody (my understanding is indeed that its use is only in the {rhs} of another, non-nore mapping).
My initial attempt was to map j key this way
Using execute here is redundant. It's enough to do:
nnoremap j :<C-U>call MyFun(v:count)<CR>
now results in the error E169: Command too recursive
That's because of normal. To suppress remapping you must use "bang"-form: normal! j. Please, refere
to documentation for :normal, whose second paragraph describes exactly your use case:
If the
[!]is given, mappings will not be used. Without it, when this command is called from a non-remappable mapping (:noremap), the argument can be mapped anyway.
Besides, note that j normally supports count, so 2j is expected to move two lines down. So you, probably, should do execute 'normal!' a:count . 'j' instead.