Re: bc and dc -e/-f and Copyright

On Thu, Jul 30, 2020 at 4:25 PM Jessica Clarke <jrtc27_at_freebsd.org> wrote:
>
> On 30 Jul 2020, at 23:21, Jessica Clarke <jrtc27_at_freebsd.org> wrote:
> > On 30 Jul 2020, at 20:35, Gavin Howard <gavin.d.howard_at_gmail.com> wrote:
> >>
> >> Hello,
> >>
> >> My name is Gavin Howard, and I am the developer and maintainer of the
> >> new bc and dc implementation in -CURRENT. Stefan Eßer brought a
> >> discussion about my bc to my attention, and I would like to solve the
> >> problems.
> >>
> >> First, I will add some way to remove the printing of the copyright
> >> header at compile time, and FreeBSD should be able to take advantage
> >> of it as soon as I put out a new release, which should be within days
> >> after this discussion is settled.
> >>
> >> Second, there seems to be those who are unhappy with my decision to
> >> make bc and dc not exit when using the -e and -f options. While the
> >> behavior of my bc is what I personally need, I have a few options to
> >> change it back to what is expected:
> >>
> >> 1. I could make it a compile-time selection. I don't like this option,
> >> to be honest.
> >>
> >> 2. I could restore the expected behavior of -e and -f and change the
> >> environment variable to BC_EXPR_NO_EXIT (DC_EXPR_NO_EXIT) and reverse
> >> the logic. I could do this one, but Stefan mentioned to me that he
> >> would prefer less environment variables be used. I agree.
> >>
> >> 3. I could restore the expected behavior of -e and -f and add -E and
> >> -F options that do the same thing but do not exit. I think I like this
> >> option the best. I am willing to change -E and -F to something else if
> >> that would be better.
> >
> > Rather than introducing new options like any of these you could instead:
> >
> > 4. Make sure -f - reads from stdin. Then just append -f - to your uses.
> >
> > 5. Overload -i when used with -e/-f to also make it not exit.
> >
> > I personally prefer 4 as it doesn't require any confusing overloading
> > (-f - should read from stdin as a well-behaved Unix tool regardless in
> > my opinion), but does come with the downside that you can't just:
> >
> >    alias bc='bc -f -'
> >
> > for your case, you'd have to instead:
> >
> >    bc() { command bc "$_at_" -f - }
> >
> > or equivalent in your shell of choice.
>
> NB: 4 already works with GNU dc. FreeBSD's old dc requires you to do -f
> /dev/stdin instead as it doesn't treat - as special but otherwise also
> works. I haven't looked to see whether your dc regards - as stdin or
> not, but -f /dev/stdin surely already works. So 4 seems the most
> consistent and/or compatible option when considering other
> implementations.
>
> Jess

All,

I have made the following changes:

bc does not print a copyright header unless the version options (-v,
-V, and --version) are given. The -q and --quiet options are no-ops,
but are kept for compatibility with GNU bc.

I have ensured that -f - works; it basically disables exiting after
processing all expressions and files given with -e and -f. I have
found a way to make this work for me personally.

If there are no objections within 24 hours or so, I will release the
changes as 3.1.4.

Gavin Howard