How to make argparse accept "-4^2+5.3*abs(-2-1)/2" string argument? WRONG TOOL

[Weatherby,Gerard]

I understand we all want to be helpful and friendly, but it seems to me that helping someone use the wrong tool for the job isn’t really helpful in the long run.

argparse is for parsing command line arguments.  It’s the wrong tool for this job.

As Chris Angelico already said: This entire thread is a massive "how can I use X to do Y?" problem.



From: Python-list <python-list-bounces+gweatherby=uchc.edu at python.org> on behalf of Thomas Passin <list1 at tompassin.net>
Date: Tuesday, January 24, 2023 at 10:23 AM
To: Mike Baskin <mikebaskin6538 at yahoo.com>, python-list at python.org <python-list at python.org>
Subject: Re: How to make argparse accept "-4^2+5.3*abs(-2-1)/2" string argument?
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On 1/24/2023 10:13 AM, Mike Baskin wrote:
> Can you stop please

It's way past time, isn't it!

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>
> On Tuesday, January 24, 2023, 10:12 AM, Thomas Passin
> <list1 at tompassin.net> wrote:
>
>     On 1/23/2023 9:12 PM, Chris Angelico wrote:
>      > On Tue, 24 Jan 2023 at 13:09, Jach Feng <jfong at ms4.hinet.net
>     <mailto:jfong at ms4.hinet.net>> wrote:
>      >>
>      >> Chris Angelico 在 2023年1月24日 星期二清晨5:00:27 [UTC+8] 的信中
>     寫道：
>      >>> On Tue, 24 Jan 2023 at 07:47, Cameron Simpson <c... at cskk.id.au
>     <mailto:c... at cskk.id.au>> wrote:
>      >>>>
>      >>>> But for Jach Feng: the "--" is really expected as something
>     the user
>      >>>> does when they invoke your programme, _explicitly_ saying that
>     what
>      >>>> follows from here is not an argument. So the user is expected
>     to type:
>      >>>>
>      >>>> your_script -x -y -- "-4^2+5.3*abs(-2-1)/2"
>      >>>>
>      >>>> where there are -x and -y options, then end of options, then an
>      >>>> argument, which would look like an option if there wasn't the "--"
>      >>>> argument.
>      >>> And if you DON'T expect the user to enter the "--", then why use
>      >>> argparse? You can just check argv directly to get your arguments.
>      >>>
>      >>> This entire thread is a massive "how can I use X to do Y?" problem.
>      >>>
>      >>> ChrisA
>      >> The '--' requirement makes its usage less instinctive, and
>     handling argv directly makes me loss the benefit of using '-h':-)
>      >
>      > if "-h" in sys.argv: usage()
>      > else: do_stuff_with(sys.argv[1:])
>      >
>      > What is argparse really doing for you?
>
>     I second this.  "if '-h' in sys.argv:"  is usually what I do.
>
>     Alternatively, you could use "--arg=" syntax and place your string
>     "-4^2+5.3*abs(-2-1)/2" its right-hand side":
>
>     infix2postfix [options] "--infix=-4^2+5.3*abs(-2-1)/2"
>
>     This shouldn't be too hard for a user to work with.  You could scan the
>     argument list for the presence of "--infix=" and display the help
>     message if it isn't there.
>
>
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