title: Cast function argument as a character string?
body: <p>Super quick question...</p>
  
  <p>How do you take a some particular function's (user-defined) argument and cast it as a character-string?</p>
  
  <p>If for a simple example,</p>
  
  <pre><code>foo &lt;- function(x) { ... }
  </code></pre>
  
  <p>I want to simply return x's object name. So,</p>
  
  <pre><code>foo(testing123)
  </code></pre>
  
  <p>returns <code>"testing123"</code> (and testing123 could just be some random numeric vector)</p>
  
  <p>Apologies if this question has been asked before--searched, but couldn't find it! Thanks!!</p>