From: Vincent Lefevre <vincent@vinc17.net>
To: zsh-users@zsh.org
Subject: Re: grammar triviality with '&&'
Date: Mon, 2 Mar 2015 11:31:56 +0100 [thread overview]
Message-ID: <20150302103156.GB6869@xvii.vinc17.org> (raw)
In-Reply-To: <150302005440.ZM16546@torch.brasslantern.com>
On 2015-03-02 00:54:40 -0800, Bart Schaefer wrote:
> On Mar 2, 3:27am, Vincent Lefevre wrote:
> }
> } However "&& [ -e file2 ]" could constitute a list too. There is
> } currently a parse error, but zsh could have an extension to accept
> } it as being equivalent to: "[[ $? -eq 0 ]] && [ -e file2 ]". Would
> } there be anything wrong with such an extension?
>
> If nothing else, the errexit option would fail. With errexit,
>
> false
> || anything
>
> would never get beyond "false", whereas
>
> false || anything
>
> proceeds at least through "anything".
I agree that's not equivalent, but this would not be a problem
in a "if ... then" construct (though I think it's a bad idea
to use such a feature here).
> You also get strange crap like
>
> while && this; do || if && that; then || thus; fi; done
>
> which would mean what, exactly?
while [[ $? -eq 0 ]] && this; do [[ $? -ne 0 ]] || if [[ $? -eq 0 ]] && that; then [[ $? -ne 0 ]] || thus; fi; done
> Finally if it's OK to have nothing before && / ||, then it would also be
> syntactically OK to write
>
> && || && || && && ...
I disagree. Only a && or || as the first word of a list would have
a special meaning.
--
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
next prev parent reply other threads:[~2015-03-02 10:32 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-01 16:07 Ray Andrews
2015-03-01 16:43 ` ZyX
2015-03-01 17:01 ` Ray Andrews
2015-03-01 18:48 ` Bart Schaefer
2015-03-01 19:00 ` ZyX
2015-03-01 19:16 ` Ray Andrews
2015-03-01 20:48 ` ZyX
2015-03-01 18:49 ` Lawrence Velázquez
2015-03-02 2:27 ` Vincent Lefevre
2015-03-02 3:12 ` Ray Andrews
2015-03-02 5:22 ` Lawrence Velázquez
2015-03-02 3:53 ` Kurtis Rader
2015-03-02 4:18 ` Ray Andrews
2015-03-02 5:22 ` Kurtis Rader
2015-03-02 16:17 ` Ray Andrews
2015-03-02 18:52 ` Kurtis Rader
2015-03-02 19:03 ` ZyX
2015-03-02 20:16 ` Kurtis Rader
2015-03-03 4:15 ` ZyX
2015-03-03 4:43 ` Kurtis Rader
2015-03-04 15:03 ` Vincent Lefevre
2015-03-04 19:07 ` ZyX
2015-03-02 19:25 ` Ray Andrews
2015-03-02 10:46 ` Vincent Lefevre
2015-03-02 11:06 ` Peter Stephenson
2015-03-02 19:19 ` Bart Schaefer
2015-03-04 14:47 ` Vincent Lefevre
2015-03-05 1:51 ` Bart Schaefer
2015-03-05 10:06 ` Peter Stephenson
2015-03-02 8:54 ` Bart Schaefer
2015-03-02 10:31 ` Vincent Lefevre [this message]
2015-03-02 16:31 ` Ray Andrews
2015-03-02 16:49 ` Bart Schaefer
2015-03-02 17:38 ` Ray Andrews
2015-03-02 18:51 ` Bart Schaefer
2015-03-04 8:55 ` Vincent Lefevre
2015-03-04 17:12 ` Ray Andrews
2015-03-06 4:59 ` Bart Schaefer
2015-03-06 16:10 ` Ray Andrews
2015-03-06 20:23 ` Lawrence Velázquez
2015-03-06 21:25 ` Ray Andrews
2015-03-06 16:32 ` Vincent Lefevre
2015-03-06 17:43 ` Bart Schaefer
2015-03-06 21:01 ` Ray Andrews
2015-03-09 11:26 ` Vincent Lefevre
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