Re: Create functional processing pipe (without eval)?

On 2025-05-07, Janis Papanagnou <janis_papanagnou+ng@hotmail.com> wrote:

I'm pondering about creating a functional processing pipe, depending
on program parameters, and whether that's possible to achieve without
using 'eval'.
>
Say, the program is called "filter" and may accept 0..N parameters and
depending on the set of parameters the respective pipe functionality
shall be defined like
>
  filter               =>  cat
  filter p1            =>  cat | func p1
  filter p1 p2         =>  cat | func p1 | func p2
  filter p1 p2 ... pN  =>  cat | func p1 | func p2 | ... | func pN
>
where "func" is working as filter and accepts exactly one parameter.
>
(Because of reservations I have with 'eval' and quoting I'd like to
avoid that 'eval' indirection if possible.)

For a limited number of arguments, you could do it with a switch,
enumerating the variations. I can see the utility of such a feature.

It seems that you could do this with a small wrapper program (in your
favorite progframming language) activating the shell once the pipeline
has been constructed.

I would like to have this king of feature wrapped around grep in order
to do compounded keyword searches, but it's not a high priority.

Lars