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Date: Wed, 23 Feb 2011 13:27:06 -0500 (EST)
From: "Benjamin R. Haskell" <zsh@benizi.com>
To: Zsh Users <zsh-users@zsh.org>
Subject: Re: Function-scoped parameters?
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On Wed, 23 Feb 2011, Benjamin R. Haskell wrote:

> This doesn't work, probably unsurprisingly.  But is there a way to 
> accomplish it?
>
> function () {
>    emulate -L zsh
>    local x=asdf
>    trap 'echo x is ${x:-unset}' EXIT
> }
>
> The use case is that I want to assign a local parameter 'temp' to be 
> set to the name of a temporary file.  If anything goes wrong in the 
> function, I'd like that temporary file to be removed, but I don't want 
> 'temp' to leak out of the function scope.
>
> e.g.:
> dosomething () {
>    emulate -L zsh
>    local temp=$(mktemp)
>    setopt err_return
>    trap '(( $+temp )) && rm $temp' EXIT
>    # ...
> }
>

Hmm.  The following seems to do what I want, but seems kludgy and 
zsh-specific (which might be fine, but this seems like something other 
shells should be able to do).  (Main problem might be that I tend to 
code as if I'm using Perl even when I'm not.)

dosomething () {
     emulate -L zsh
     setopt err_return
     local temp=$(mktemp)
     function () {
         trap '(( $+temp )) && rm $temp' EXIT
         # ... do stuff ...
     }
     # at this point, $temp has always been cleaned up (error or no)
}
dosomething blah blah
# at this point, $temp is not leaked

-- 
Best,
Ben