From: Robert Klemme <bob.news@...>
Date: 2006-02-05T03:53:19+09:00
Subject: Re: Extract hash into local variables?

Jeffrey Schwab <jeff@schwabcenter.com> wrote:
> csn wrote:
>> Is there a Ruby function similar to PHP's extract/list? What I'd
>> like to do is:
>>
>> def foo(args={a=>1, b=>2, c=>3})
>>   args.extract
>>
>>   puts a
>>   puts b
>>   puts c
>> end
>
> I'm kind of disturbed by how hard this actually seems.  There does not
> seem to be any decent way to modify the set of local variables through
> introspection.  Here's a weak work-around:
>
>
> def foo(args={:a=>1, :b=>2, :c=>3})
>   @args = args
>
>   def method_missing(m)
>     @args[m]
>   end
>
>   puts a
>   puts b
>   puts c
>
> end

Very weak.  This is by no means thread safe. Also it will keep references to 
the arguments around after the method terminates.  Plus, you're redefining 
method_missing all the time.  Too many drawbacks IMHO.

I don't know why people strive to get local variables set dynamically.  If 
you want to use them, you'll have to make them explicitely anyway.  So what 
do we gain?  Is there a real world problem that can't be solved without 
this?

Cheers

robert