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Date: Fri, 30 Sep 2016 07:45:09 +0000
From: Daniel Shahaf <d.s@daniel.shahaf.name>
To: Ignatius Reilly <turnbuckle@gmail.com>
Cc: zsh-users@zsh.org
Subject: Re: Passing array to function
Message-ID: <20160930074509.GA2554@fujitsu.shahaf.local2>
References: <1A643BF6-28C9-483E-9312-D8C856D41F0D__26800.772539764$1475219850$gmane$org@gmail.com>
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User-Agent: Mutt/1.5.23 (2014-03-12)

Ignatius Reilly wrote on Fri, Sep 30, 2016 at 02:15:55 -0500:
> addtoarray() { [[ -d $1 ]] && myarray=($1 $myarray) }
> 
> which works as expected, prepending an element to an array only if its an
> existing directory.  I'd like to rewrite this function so that I can pass
> the array name as a parameter like so:
> 
> addtoarray /usr/foo myarray

You could do it with eval:

addtoarray() {
  [[ -d $1 ]] && eval "${(q)2}[1,0]=${(q)1}"
}

Explanation:

- The (q) are there to convert the values to command-line-quoted
  strings, for eval.  $2 probably needs no quoting — if it did, the eval
  would see a syntax error — but I put the (q) anyway to guard against
  invalid inputs (bobby tables attacks against the eval).

- After parameter substitution, the resultant string is:
    myarray[1,0]=/usr/foo
  which is a slice assignment that prepends an element to the named
  array.

If there's a solution without eval I'm sure someone will post it.

Cheers,

Daniel


> Thanks
>