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From: Bart Schaefer <schaefer@brasslantern.com>
To: zzapper <zsh@rayninfo.co.uk>
Cc: Zsh-Users List <zsh-users@zsh.org>
Subject: Re: Can I test if a parameter expansion has worked
Date: Wed, 14 Sep 2022 11:36:38 -0700	[thread overview]
Message-ID: <CAH+w=7aLhYhSNFKU1Z=ZM4fGSQ2dLUSr+akwtN2Ec_vNyqeHrg@mail.gmail.com> (raw)
In-Reply-To: <5dc8b935-f234-ca54-0ceb-50cb1da9bc29@rayninfo.co.uk>

On Wed, Sep 14, 2022 at 9:52 AM zzapper <zsh@rayninfo.co.uk> wrote:
>
> Q1) Can I test if a parameter expansion has 'fired'?

I'm not sure what that means.  Does 'fired' mean expanded to a
non-empty string, as in, the parameter has a value?  And, test when,
relative to the placement of the parameter reference?  And, what do
you want to do based on the result of the test?

The most obvious answer would be that ${param:?} will cause a fatal
error if the parameter is either unset or empty, but that doesn't
provide any avenue for recovery unless you use an "always" block
around it.


  reply	other threads:[~2022-09-14 18:38 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-14 10:03 zzapper
2022-09-14 18:36 ` Bart Schaefer [this message]
2022-09-15  0:08 ` Alex Satrapa
2022-09-15  7:34 ` zzapper
2022-09-15  8:24   ` Peter Stephenson
2022-09-15  8:38     ` zzapper
2022-09-15 16:48   ` Bart Schaefer
2022-09-20  7:14     ` david rayner
2022-09-16  0:41   ` Alex Satrapa
2022-09-20 12:49   ` Stephane Chazelas
2022-09-20 13:25   ` Stephane Chazelas
2022-09-20 13:31     ` Stephane Chazelas

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