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From: Bart Schaefer <schaefer@brasslantern.com>
To: Daniel Shahaf <d.s@daniel.shahaf.name>
Cc: Zsh hackers list <zsh-workers@zsh.org>
Subject: Re: zmathfunc: min, max, sum throw error if result equals 0
Date: Fri, 16 Apr 2021 13:05:13 -0700	[thread overview]
Message-ID: <CAH+w=7aBmf8eW8kAkKjBip70rcdCor3f-bwf1ZMeTUziw4ZJAQ@mail.gmail.com> (raw)
In-Reply-To: <20210416195028.GE15670@tarpaulin.shahaf.local2>

On Fri, Apr 16, 2021 at 12:51 PM Daniel Shahaf <d.s@daniel.shahaf.name> wrote:
>
> [...] the first one interpolates $arg as in double-quoted strings
> and then parses the string " x += 2 > result ", where the > operator has
> higher precedence, and «2 > result» evaluates to 1, and the «print» then
> evaluates everything left to right; whereas the latter sees «arg» and
> tries to evaluate that _as a number_, which works out to 2 (with a side
> effect), so the condition evaluates to true, and the assignment on the
> RHS then works out to 4 (with a side effect).  Clear as a cloudless day

Given that, I'm puzzled why you did

> +    (( $arg < result ))
> +    case $? in
> +      (0) result=$arg;;
> +      (1) ;;
> +      (*) return $?;;
> +    esac
>    done
>    (( result ))

and why not

  (( arg < result ))
  case $? in
    (0) (( result = arg ));;
    (1) ;;
    (*) return $?;;
  esac
done
(( result ))

??  The (( $arg < result )) formulation still potentially has
different operator precedence in and out of math context, and
result=$arg followed by (( result )) still does repeat interpretation
of $arg.  Why ever interpolate $arg as a string?


  reply	other threads:[~2021-04-16 20:05 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-07 16:37 Nikolaus Thiel
2021-03-07 17:17 ` Daniel Shahaf
2021-03-07 21:39   ` Bart Schaefer
2021-03-07 21:56     ` Daniel Shahaf
2021-03-08  2:25       ` Bart Schaefer
2021-04-16 18:26         ` Daniel Shahaf
2021-04-16 18:47           ` Bart Schaefer
2021-04-16 19:50         ` Daniel Shahaf
2021-04-16 20:05           ` Bart Schaefer [this message]
2021-04-16 20:08             ` Daniel Shahaf
2021-04-16 18:21   ` Daniel Shahaf
2021-05-16 14:54     ` Lawrence Velázquez
2021-05-18  2:02       ` Daniel Shahaf

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