title: Using dplyr `enquo` after calling argument
body: <p>I have a function that roughly follows this structure:</p>
  
  <pre><code>TestFunc &lt;- function(dat, point) {
      if (!(point %in% c("NW", "SE", "SW"))) 
          stop("point must be one of 'SW', 'SE', 'NW'")
  
      point &lt;- enquo(point)
  
      return(dat %&gt;% filter(point == !!point))
  </code></pre>
  
  <p>The issue is that I get the following error when I include the check for values:</p>
  
  <pre><code>Error in (function (x, strict = TRUE)  : 
    the argument has already been evaluated
  </code></pre>
  
  <p>The error disappears when I remove the check.  How can I keep both?</p>