Function-scoped parameters?

["Benjamin R. Haskell" <zsh@benizi.com>]

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
     # ...
}

-- 
Best,
Ben