Local inner functions in a prompt

Local inner functions in a prompt

[Eric Nielsen]

Hi all,

I'm aware of https://www.zsh.org/mla/users/2011/msg00207.html and that there's no such thing as an inner function.

But I'm surprised to see that if I declare "inner" functions inside a prompt function, they are not visible from "outside".

To reproduce this:

% cat <<'EOF' >prompt_outer_setup
prompt_outer_main() {
  local -i foo=1
  increment_foo() {
    (( foo++ ))
  }
  print_foo() {
    print -n ${foo}
  }
  inner1() {
    increment_foo
  }
  inner2() {
    increment_foo
  }
  inner1
  inner2
  print_foo
}
prompt_outer_setup() {
  PS1='$(prompt_outer_main)%# '
}
prompt_outer_setup
EOF
% fpath+=(${PWD})
% autoload -Uz promptinit && promptinit
% prompt outer
3%  print ${+functions[prompt_outer_setup]}
1
3%  print ${+functions[prompt_outer_main]}
1
3%  print ${+functions[increment_foo]}
0
3%  print ${+functions[print_foo]}
0
3%  print ${+functions[inner1]}
0
3%  print ${+functions[inner2]}
0
3%

As you can see only the "outer" functions prompt_outer_setup and prompt_outer_main are declared in the functions array. And the "inner" functions can access the local variable from the "outer" function, and an "inner" function can call other "inner" functions.

Is this scenario causing an unexpected behavior in Zsh, or is it really possible to create "inner" functions for prompts?

Kind regards,
Eric

Re: Local inner functions in a prompt

[Mikael Magnusson]

On 12/21/18, Eric Nielsen <eric@amalgamar.com.br> wrote:
> Hi all,
>
> I'm aware of https://www.zsh.org/mla/users/2011/msg00207.html and that
> there's no such thing as an inner function.
>
> But I'm surprised to see that if I declare "inner" functions inside a prompt
> function, they are not visible from "outside".
> prompt_outer_setup() {
>   PS1='$(prompt_outer_main)%# '
> }
> prompt_outer_setup

You're running the function in a subshell here.

-- 
Mikael Magnusson

Re: Local inner functions in a prompt

[Eric Nielsen]

Hi Mikael,
 
> On 12/21/18, Eric Nielsen <eric@amalgamar.com.br> wrote:
>> Hi all,
>>
>> I'm aware of https://www.zsh.org/mla/users/2011/msg00207.html and that
>> there's no such thing as an inner function.
>>
>> But I'm surprised to see that if I declare "inner" functions inside a prompt
>> function, they are not visible from "outside".
>> prompt_outer_setup() {
>>   PS1='$(prompt_outer_main)%# '
>> }
>> prompt_outer_setup
>
> You're running the function in a subshell here.

Oh, of course! (facepalm)

Do you recommend a better way to have a similar structure (one function that is called inside the prompt, that needs to call other functions), or my code structure is completely fine?

Thanks,
Eric