From: Joel VanderWerf <vjoel@...>
Date: 2005-02-18T05:22:37+09:00
Subject: Re: Evaluating a string of Ruby code within an anonymous module: done correctly?

Joel VanderWerf wrote:
> Here's an even simpler way, just wrapping the code in a proc, which may 
> be suitable for small snippets of code:
> 
> def eval_string(s, *args_to_pass)
>     pr = eval("proc do |*args| #{s.to_str} end")
>     pr[*args_to_pass]
> end
> 
> eval_string(<<EOL, [1, 2, 3, 4, 5])
>   b = args.collect {|i| i*3}
>   c = b.join("||")
>   puts(c)
> EOL
> 
> Warning: the binding of the "pr" local variable and the two arg 
> variables is still in effect wthin the proc, so this may not be 
> suitable. Or you could use very obscure names and hope.

Just realized how to fix that:

def empty_binding
   binding
end

def eval_string(s, *args_to_pass)
     pr = eval("proc do |*args| #{s.to_str} end", empty_binding)
     pr[*args_to_pass]
end

eval_string(<<EOL, [1, 2, 3, 4, 5])
   b = args.collect {|i| i*3}
   c = b.join("||")
   puts(c)
   #p pr #<-- now this fails
EOL