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From: Paul Winalski <paul.winalski@gmail.com>
To: Michael Siegel <msi@malbolge.net>
Cc: tuhs@minnie.tuhs.org
Subject: Re: [TUHS] Systematic approach to command-line interfaces
Date: Sat, 31 Jul 2021 11:56:51 -0400	[thread overview]
Message-ID: <CABH=_VR-tfenCLE=DeNcb2ahPjG80v6Ma+W0sRt2jAfy2OX4hg@mail.gmail.com> (raw)
In-Reply-To: <20210731142533.69caf929@moon>

On 7/31/21, Michael Siegel <msi@malbolge.net> wrote:
>
> While doing that, I learned that there is a better way to approach
> this problem – beyond using getopt(s) (which never really made sense to
> me) and having to write case statements in loops every time: Define a
> grammar, let a pre-built parser do the work, and have the parser
> provide the results to the program.

This method for handling command lines dates back at least to the
1970s.  The COMND JSYS (system call) in TOPS-20 operated this way, as
does the DCL command line interface in OpenVMS.  As you pointed out it
can greatly simplify the code in the application.  It also permits
command completion.  If the command has a long-winded option, such as
-supercalifragilisticexpialidocious, I can type -super then hit the
TAB key and as long as there is only one option that starts with
-super the parser will fill in the rest of the long keyword.  It also
means that you can provide interactive help.  At any point the user
can type a question mark and the command interpreter will say what
syntactic element is expected next.  The TOPS-20 COMND JSYS
implemented both of these features, and I think that command
completion was eventually added to the VMS command interpreter, too.

This method of command line parsing also enforces a degree of
uniformity of syntax between the command lines of the various
utilities and applications.

-Paul W.

  parent reply	other threads:[~2021-07-31 15:57 UTC|newest]

Thread overview: 100+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-31 12:25 Michael Siegel
2021-07-31 13:05 ` Dan Halbert
2021-07-31 14:21 ` Adam Thornton
2021-07-31 14:25   ` Adam Thornton
2021-07-31 15:45 ` Richard Salz
2021-07-31 16:03   ` Clem Cole
2021-07-31 16:06     ` Richard Salz
2021-07-31 16:21       ` Clem Cole
2021-07-31 16:17     ` Clem Cole
2021-07-31 16:30       ` Dan Cross
2021-07-31 15:56 ` Paul Winalski [this message]
2021-07-31 16:19   ` Dan Cross
2021-08-01 17:44     ` Chet Ramey
2021-08-01 21:53       ` Dan Cross
2021-08-01 23:21         ` Chet Ramey
2021-08-01 23:36         ` John Cowan
2021-08-01 23:49           ` Larry McVoy
2021-08-02  0:28             ` Larry McVoy
2021-08-01 23:58           ` Dan Cross
2021-08-02  0:29             ` Steve Nickolas
2021-08-02  0:13           ` Andrew Warkentin
2021-08-02  0:18             ` John Cowan
2021-08-02  0:54               ` Andrew Warkentin
2021-08-02  1:04               ` Dan Cross
2021-08-02  1:05             ` Theodore Ts'o
2021-08-02  2:10               ` Andrew Warkentin
2021-08-02  2:32               ` Bakul Shah
2021-08-02 17:33             ` Lars Brinkhoff
2021-09-28 17:46             ` Greg A. Woods
2021-09-28 18:10               ` Larry McVoy
2021-09-29 16:40                 ` Greg A. Woods
2021-09-29 16:57                   ` Larry McVoy
2021-09-30 17:31                     ` Greg A. Woods
2021-09-29 23:10               ` Phil Budne
2021-08-02 17:37           ` Lars Brinkhoff
2021-08-02 18:52             ` Clem Cole
2021-08-02 20:59               ` John Cowan
2021-08-02 21:06                 ` Al Kossow
2021-08-02 21:14                 ` Clem Cole
2021-08-02 21:13               ` Clem Cole
2021-08-01 16:51   ` Michael Siegel
2021-08-01 17:31     ` Jon Steinhart
2021-07-31 16:41 ` Clem Cole
2021-07-31 17:41   ` John Cowan
2021-07-31 17:30 ` Anthony Martin
2021-07-31 17:46   ` John Cowan
2021-07-31 18:56   ` Michael Siegel
2021-07-31 19:41     ` Clem Cole
2021-07-31 21:30       ` Michael Siegel
2021-08-01 17:48     ` Chet Ramey
2021-08-01 19:23       ` Richard Salz
2021-08-01 23:26         ` Chet Ramey
2021-07-31 19:20 ` [TUHS] Systematic approach to command-line interfaces [ meta issues ] Jon Steinhart
2021-07-31 21:06   ` Richard Salz
2021-07-31 21:32     ` Jon Steinhart
2021-07-31 21:37       ` Richard Salz
2021-07-31 21:55         ` Jon Steinhart
2021-07-31 22:10       ` Warner Losh
2021-07-31 22:19         ` Larry McVoy
2021-07-31 22:20         ` Jon Steinhart
2021-07-31 23:26           ` Warner Losh
2021-07-31 23:41             ` Jon Steinhart
2021-07-31 22:04   ` Bakul Shah
2021-07-31 22:13     ` Larry McVoy
2021-07-31 22:14       ` Bakul Shah
2021-07-31 22:17         ` Bakul Shah
2021-07-31 22:16     ` Jon Steinhart
2021-07-31 22:20       ` Bakul Shah
2021-07-31 16:27 [TUHS] Systematic approach to command-line interfaces Nelson H. F. Beebe
2021-07-31 16:47 Ron Young
2021-08-02  2:34 ` Jim Carpenter
2021-08-02  2:38   ` Ron Young
2021-08-02  2:42 Douglas McIlroy
2021-08-02 14:58 ` Theodore Ts'o
2021-08-02 18:15   ` Adam Thornton
2021-08-02 18:24     ` Warner Losh
2021-08-02 20:55     ` John Cowan
2021-08-02 21:06       ` Jon Steinhart
2021-08-02 21:25         ` Dan Cross
2021-08-02 21:59           ` Jon Steinhart
2021-08-02 22:33             ` John Cowan
2021-08-03  0:21     ` Bakul Shah
2021-08-03  1:49       ` Jon Steinhart
2021-08-03  3:21         ` Adam Thornton
2021-08-03  3:27         ` Bakul Shah
2021-08-03  3:51           ` Jon Steinhart
2021-08-03  7:19   ` arnold
2021-08-03 23:12     ` Andrew Warkentin
2021-08-04 15:04       ` Paul Winalski
2021-08-03 15:01 Douglas McIlroy
2021-08-03 17:13 ` Tom Lyon via TUHS
2021-08-11 18:11   ` Tom Ivar Helbekkmo via TUHS
2021-08-11 21:24     ` Tom Lyon via TUHS
2021-08-03 19:12 Douglas McIlroy
2021-09-28 18:15 Noel Chiappa
2021-09-29 18:07 Noel Chiappa
2021-09-29 19:04 ` Dan Cross
2021-09-29 19:12 ` Larry McVoy
2021-09-30 11:41 Douglas McIlroy
2021-10-01 12:11 Paul Ruizendaal

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