From: matt@... (matt neuburg)
Date: 2006-11-12T05:10:05+09:00
Subject: Re: eval question

Peter Szinek <peter@rubyrailways.com> wrote:

> Hi,
> 
> I am setting up a few variables based on user input with the following
> code snippet:
> 
> ==================================
> vars = %w{a b c}
> 
> vars.each do |var|
>   print "#{var} = "
>   val = gets
>   eval("$#{var}=#{val.chomp}")
> end
> 
> #use a, b, c here for something
> ==================================
> 
> What I don't like about this code is the use of global variables.
> However, I have to use them - or otherwise a,b,c will be already out of
> scope at the place I need them.
> 
> Another possibility would be to use constants, i.e.
> 
> vars = %w{A B C}
> 
> which would work well - however, since I am repeating the process more
> times, from the second iteration on I am getting warnings that A, B, C
> etc were already initialized, which is not nice.
> 
> I guess yet another possibility would be to wrap a class around this
> stuff and use instance_eval or something like that - but a class that
> serves solely this purpose looks to heavy to me...
> 
> Any other ideas?

Pass a binding?

a = 1
b = 2
c = 3

def goforit(w, bind)
  w.each do |v|
    eval("#{v} = 'heehee'", bind)
  end
end

goforit %w{a b c}, binding
puts a, b, c

m.

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