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Date: Sat, 26 Sep 2015 19:57:23 +0200
Message-ID: <CAHYJk3STx4m2ySAsBRjP2Dr_7HXEuiRr05sb6UT+TszsE3VgPg@mail.gmail.com>
Subject: Re: question about parameter expansion
From: Mikael Magnusson <mikachu@gmail.com>
To: ZyX <kp-pav@yandex.ru>
Cc: Dmitri Vereshchagin <dmitri.vereshchagin@gmail.com>, Zsh Users <zsh-users@zsh.org>
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On Sat, Sep 26, 2015 at 7:41 PM, ZyX <kp-pav@yandex.ru> wrote:
> 26.09.2015, 16:38, "Mikael Magnusson" <mikachu@gmail.com>:
>> On Sat, Sep 26, 2015 at 12:18 PM, Dmitri Vereshchagin
>> <dmitri.vereshchagin@gmail.com> wrote:
>>>  Hello.
>>>
>>>  Here is a code sample I would like to rewrite using parameter expansion
>>>
>>>    if (( ${+foo} )); then
>>>      bar=
>>>    else
>>>      bar=baz
>>>    fi
>>>
>>>  Cannot find it in the docs, but I suppose there is a way to do that. Am
>>>  I right?
>>>
>>>  Thanks.
>>>
>>>  --
>>>  Dmitri Vereshchagin
>>
>> You have to think outside the box for this one,
>> bar=${${${+foo}#1}//0/baz}
>
> Why not simply
>
>     bar=${foo+baz}
>
> ?

The main reason would be that it doesn't do what OP asked for.

-- 
Mikael Magnusson