How to map shortcut to double square brackets?

Question

When I type [[ or ]] in normal mode, cursor is jumping previous / next "class definition" during editing python (.py) file.

I want to map these shortcuts to SHIFT + UP and SHIFT + DOWN. And I added this to my vimrc:

nnoremap <S-Up> [[
nnoremap <S-Down> ]]

But when I press SHIFT + UP, cursor going beginning of the file, or if I press SHIFT + DOWN, cursor going end of the file.

How can I map these keys?

Answer 1

nnoremap <S-Up> [[
nnoremap <S-Down> ]]

With the non-recursive mappings above in your vimrc, pressing <S-Up> will be exactly like pressing [[ in its original meaning.

The original meaning of [[ is (quoting :help [[):

[[    [count] sections backward or to the previous '{' in
      the first column.

which, usually, means "jump to the first column of the first line". Same logic for ]].

Since you are using non-recursive mappings, the original meaning of [[ and ]] is used, not the remapped versions from the Python filetype plugin.

You need recursive mappings:

nmap <S-Up> [[
nmap <S-Down> ]]

The rule is:

Use a recursive mapping only if you intend to use any other mapping in your mapping. Use non-recursive mappings if you don't.