Re: Global Aliases, but as a function?

[Daniel Shahaf <d.s@xxxxxxxxxxxxxxxxxx>]

Bart Schaefer wrote on Mon, Dec 20, 2021 at 17:55:15 -0800:
> You'd be looking at the third argument passed to preexec ("... the
> full text that is being executed") which you will have to take apart
> with something like cmdline=(${(z)3}) to figure out whether it's a
> simple command and whether one of the arguments is "--help".
> 

If INTERACTIVE_COMMENTS is set then the taking apart should use ${(zZ+c+)}.

> Assuming it is just one command and has that argument, you've got the
> command name in $cmdline[1] (in my foregoing example) so you're going
> to create function with that name that ends by deleting itself; e.g.
> (naively again, ignoring the "is this a simple command" test):
> 
> preexec() {
>   local cmdline=(${(z)3})
>   if [[ -n $cmdline[(R)--help] ]]; then
>     function $cmdline[1] {
>      $cmdline[1] "$@" | $LESS
>      unfunction $cmdline[1]

The parameter «cmdline» will have been undefined by the time the inner
function runs, and the first line of the inner function would infinite
loop.  Therefore:
.
    eval "function ${(qq)cmdline[1]} {
        unfunction -- ${(q)cmdline[1]}
        ${(q)cmdline[1]} "\$@" | …
    }"

>

For the "is this a simple command?" test, my first sketch would be:

- No command separator tokens (';', '|', '||', etc.)

- First word's «type» is «command» [this rules out reserved words,
  assignments, aliases, functions, parameter expansions, history
  expansions…]

>     }
>   fi
> }
> 
> And you're done.  This works as long as $cmdline[1] isn't already
> defined as a different function, in which case you have to figure out
> how to save and restore that.

«functions -c»?

Cheers,

Daniel