From: Joel VanderWerf <vjoel@...>
Date: 2003-03-18T17:19:43+09:00
Subject: Re: Substitution in a string in a string

Tim Bates wrote:
> I am using eval to dynamically define a method, and at some point, I want to 
> do this:
>   raise "Invalid type: #{val}"
> Except that this is inside an eval'd string, and so #{val} gets evaluated the 
> first time, and at this point val doesn't exist. I've tried all sorts of 
> things like
>   raise "Invalid type: #{"#{val}"}"
> but none of them quite do what I want. I eventually settled for
>   raise "Invalid type: " + val.to_s
> but it still raises the question, how do you force a #{...} not to be 
> evaluated?
> 
> Tim Bates

It's so obvious, it's easy to miss:

eval %{
   def greet name
     puts "Hello, \#{name}"
   end
}

greet "Fred"