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From: Bart Schaefer <schaefer@brasslantern.com>
To: zsh-users@zsh.org
Subject: Re: suprise with -=
Date: Mon, 19 Oct 2015 17:27:44 -0700	[thread overview]
Message-ID: <151019172744.ZM558@torch.brasslantern.com> (raw)
In-Reply-To: <562545DD.5020008@eastlink.ca>

On Oct 19, 12:34pm, Ray Andrews wrote:
}
} [...] declare variable types, which is what I'm trying to do with
} 'integer' and after that I'd expect both increment and decrement to
} behave the same way.

The parser doesn't know that "first" is an integer, or even that it's
a variable that was previously declared.  This is perfectly legal:

    if (( RANDOM % 7 ))
    then integer first
    else declare first
    fi
    first+=second

(Which is why I'm inclined to say it ought to always be string context
when not explicitly math context, but it's probably way to late for that.)

} I'd consider it very rude for any forcible conversions to occur.
} Better an error, tho again once one has declared an integer one might
} expect one's operators to behave consistently.

Note:

torch% integer first=1 second=2
torch% first+=(second)
torch% echo $first
1 second

This has silently forced $first to change into an array because of
explicit array context; it did not interpret "(second)" as arithmetic
parens.

Also just to mess things up a bit more:

torch% integer first=1 second=2
torch% third=first+second
torch% print $third
first+second
torch% integer third             
torch% print $third
3

If something has a string value and you re-declare it integer, it does
math on its string value.  Doesn't happen for array to integer.


  reply	other threads:[~2015-10-20  0:27 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-10-19  5:46 Ray Andrews
2015-10-19 18:35 ` Bart Schaefer
2015-10-19 19:34   ` Ray Andrews
2015-10-20  0:27     ` Bart Schaefer [this message]
2015-10-21  2:55       ` Ray Andrews
2015-10-21  3:52         ` Bart Schaefer
2015-10-21 18:01       ` Ray Andrews
2015-10-21 18:43         ` ZyX
2015-10-22 15:29           ` Ray Andrews
2015-10-22 15:43             ` ZyX
2015-10-22 16:02               ` Ray Andrews
2015-10-22 23:56               ` Bart Schaefer
2015-10-23  7:34                 ` Daniel Shahaf
2015-10-21 18:46         ` Bart Schaefer

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