title: How to refer to variable instead of column with dplyr
body: <p>When using dplyr:filter, I often compute a local variable that holds the viable choices:</p>
  
  <pre><code>df &lt;- as_tibble(data.frame(id=c("a","b"), val=1:6))
  ids &lt;- c("b","c")
  filter(df, id %in% ids)
  # giving id %in% c("b","c")
  </code></pre>
  
  <p>However, if the dataset by chance has a column with the same name, this fails to achieve the intended purpose:</p>
  
  <pre><code>df$ids &lt;- "a"
  filter(df, id %in% ids)
  # giving id %in% "a"
  </code></pre>
  
  <p>How should I explicitly refer to the ids variable instead of the ids column?</p>