Re: Determining whether a function is used in an arithmetic context

[dana <dana@xxxxxxx>]

I suppose that'll do. Thanks!


On 25 July 2017 at 02:03, Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx> wrote:

> On Mon, Jul 24, 2017 at 8:47 PM, dana <dana@xxxxxxx> wrote:
> >
> > I was playing with arithmetic functions recently and i wanted to have one
> > of them behave differently depending on whether it's used in an
> arithmetic
> > context or not. I can't seem to figure out a *reliable* way to detect
> that
>
> I guess I'd do it like this:
>
> myfunc() {
>   if [[ ${funcstack[2]} == myfunc_math ]]
>   then print In math context
>   else print Not in math context
>   fi
> }
> myfunc_math() {
>   myfunc "$@"
> }
>
> functions -M myfunc 1 1 myfunc_math
>
> > The %_ prompt expansion seemed like it might be the way to go — it
> produces
> > math when used in an arithmetic command... but not an arithmetic
> > *substitution*, strangely. (Is that expected?)
>
> Yes, it's expected, because it's the parser state -- by the time the
> function is
> actually executing, the parser is done.  %_ is only meaningful during
> program
> input (typically interactively) or in an execution trace, not during
> execution itself.
> I think it's accidental that it has a value during arithmetic commands.
>