From: "Bart Schaefer" <schaefer@candle.brasslantern.com>
To: Phil Pennock <phil@psidev.net>, Zsh Users <zsh-users@sunsite.auc.dk>
Subject: Re: expansion of nested parameters
Date: Mon, 22 Nov 1999 20:14:53 +0000 [thread overview]
Message-ID: <991122201453.ZM23495@candle.brasslantern.com> (raw)
In-Reply-To: <19991122190225.A8613@psidev.net>
On Nov 22, 7:02pm, Phil Pennock wrote:
} Subject: expansion of nested parameters
}
} This is with zsh-3.0.7:
} -----------------------------< cut here >-------------------------------
} #!/bin/zsh -f
} a=foo
} wib_foo_ble=Wow
} c=\$wib_${a}_ble
} print ${(e)c}
} print ${(e)\$wib_${a}_ble}
} -----------------------------< cut here >-------------------------------
}
} 1: Why does the second print statement print out the current process ID
} from $$ instead of printing the same as the first print statement?
${(e)c} means: Expand ${c}, then apply command substitution etc. to the
result of that expansion.
Hence ${(e)\$wib_${a}_ble} means: Expand ${\$wib_${a}_ble}, then ...
You'll note that ${\$} is the same as ${$} because the command-line parser
strips the backslash before the parameter-name interpreter ever gets around
to looking at it. ${$} is the same as $$; the rest of the "wib_${a}_ble"
stuff is simply ignored once zsh recognizes $$.
} 2: Is there a way to do this without using an intermediate variable, as
} I've done with $c and without using eval statements?
Yeah; it's in the FAQ, question 3.22. What you're asking is a variation:
print ${(e)a:+\$wib_${a}_ble}
should do it.
--
Bart Schaefer Brass Lantern Enterprises
http://www.well.com/user/barts http://www.brasslantern.com
prev parent reply other threads:[~1999-11-22 20:15 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-11-22 19:02 Phil Pennock
1999-11-22 19:34 ` Zefram
1999-11-22 20:14 ` Bart Schaefer [this message]
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