title: Ruby grep with string argument
body: <p>I want to use grep with a string as regex pattern. How can i do that?</p>
  
  <p>Example:</p>
  
  <pre><code>myArray.grep(/asd/i) #Works perfectly.
  </code></pre>
  
  <p>But i want to prepare my statement first</p>
  
  <pre><code>searchString = '/asd/i'
  myArray.grep(searchString) # Fails
  </code></pre>
  
  <p>How can i achieve this? I need a string prepared because this is going into a search algorithm and query is going to change on every request.
  Thanks.</p>