title: How to do "late" string interpolation in Ruby
body: <pre><code>&gt;&gt; string = '#{var}'
  =&gt; "\#{var}"
  
  &gt;&gt; proc = Proc.new { |var| string }
  =&gt; #&lt;Proc:0xb717a8c4@(pry):6&gt;
  
  &gt;&gt; proc.call(123)
  =&gt; "\#{var}"
  </code></pre>
  
  <p>Not really what I want. Double quotes around <code>string</code> result in the obvious <code>undefined local variable</code>.</p>