jupyter_core Complete notebook files in ZSH completion

Hi, I’m trying to get jupyter notebook <tab> to show me both subcommands and notebook files as options here.

sadly i don’t seem to get what’s going on. whatever i tried, it throws errors at some point.

can somebody explain how it works? my progress:

${(P)subcmd}} means “expand to the value of the variable named $subcmd”. i.e. if subcmd=notebook, it expands to $notebook, which is previously set to the output of $(jupyter notebook --help-all | grep … | sed …)

so ${(P)subcmd}} aka $notebook (in one branch) holds the _arguments-formatted options to the notebook subcommand
_${subcmd}_cmds aka _notebook_cmds (in one branch) holds _describe output.

below my most recent attempts:

eval-string
```
_alternative \
  'notebook:notebook:_files -g "*.ipynb"' \
  "subcommands:subcommands:{_${subcmd}_cmds && echo ${(P)subcmd}}" && ret=0
```
at some point it prints the stuff instead of using it… do i have to do this? is there a better way? _alternative … "subcommands:subcommands:{$(_${subcmd}_cmds && echo ${(P)subcmd})}"

function

_cmds_and_opts() {
    _${subcmd}_cmds
    echo ${(P)subcmd}
}
_alternative \
  'notebook:notebook:_files -g "*.ipynb"' \
  "subcommands:subcommands:_cmds_and_opts" && ret=0

huh? can’t i redefine functions? or what’s wrong