Re: Can zsh `else` reserved keyword command be aliased and the lexem itself be repurposed as `fi` keyword command?

[mathieu stumpf guntz <psychoslave@culture-libre.org>]

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On a side note, the line `enable -r else; if true; then else fi; disable 
-r else` won't work with two execution in a row:

      ▶ enable -r else; if true; then else fi; disable -r else # works
      ▶ export LANC=C enable -r else; if true; then else fi; disable -r else
      fi # added to close the `if`
      => export: not valid in this context: -r

Is there a way to force execution at some point on a single line, as if 
there was performed on two lines?


Le 28/12/2017 à 16:07, mathieu stumpf guntz a écrit :
> Hi everybody,
>
> This is mostly a copy of [a question already posted on 
> stackoverflow](https://stackoverflow.com/questions/48006335/can-zsh-else-reserved-keyword-command-be-aliased-and-the-lexem-itself-be-repur). 
> Maybe it might have more chance to get an answer over here.
>
> # The problem
>
> Following [ZSH: Call in-built function from zsh function that uses the 
> same 
> name](https://stackoverflow.com/questions/37498409/zsh-call-in-built-function-from-zsh-function-that-uses-the-same-name) 
> and [Run a command that is shadowed by an 
> alias](https://unix.stackexchange.com/questions/39291/run-a-command-that-is-shadowed-by-an-alias#39296), 
> it might be expected that a command `keyword` equivalent of what 
> `builtin` and `command` are doing for their respective eponymous token 
> category; so that
>
>     if [ -z 'love' ]; then echo 'sad world'; keyword else echo 
> 'wonderful world'; fi
>
> would be equivalent to
>
>     if [ -z 'love' ]; then echo 'sad world'; else echo 'wonderful 
> world'; fi
>
> This problem was found in the following tricky scenario: being able to 
> replace `else` with `alie` and `fi` with `else`. See [Can zsh 
> buildtins be 
> aliased?](https://stackoverflow.com/questions/47999451/can-zsh-buildtins-be-aliased) 
> for more details.
>
> So an hypothetical attempt to implement that, if the `keyword` command 
> existed, would be:
>
>   alias alie="keyword else"
>   alias else='fi'
>
> # Summary
>
> So, to sum it up, the question is how do you make the following peace 
> of zsh code works as expected by the previous command:
>
>     if [ -z 'love' ]; then echo 'sad world'; alie echo 'wonderful 
> world'; else
>
> # A first trail
>
> This is not yet a working solution, but here is an idea: using the 
> `-r` flag of `enable` and `disable` builtin commands to change 
> visibility of the `else` keyword. So:
>
>     alias se='enable -r else; if'
>     alias alie='else'
>     disable -r else
>     alias else="fi; disable -r else"
>
> This unfortunately doesn't work
>
>     se [ -z 'amo' ]; then echo 'trista mondo'; alie echo 'mirinda 
> mondo'; else
>     # zsh: parse error near `fi'
>
> This is however supposedly on the "else" alias substitution that 
> something break, as a non-inline version will indeed enter the 
> else-branch and print "mirinda mondo".
>
> Kind regards
>
>