title: Change variable outside of reactive function/context
body: <p>I am looking for a way to change a variable, which has been initialized outside of the reactivity context in a shiny app.</p>
  
  <p>Meaning: I have two variables which I need to set, depending on what happens in the shiny app, to <code>TRUE</code> or <code>FALSE</code>.</p>
  
  <p>That needs to be done from an an reactive function.</p>
  
  <p>Example:</p>
  
  <pre><code>a &lt;- FALSE
  c &lt;- FALSE
  
  observeEvent(input$test, { #this triggers c to change to TRUE
      a &lt;- FALSE
      c &lt;- TRUE
  )}
  </code></pre>
  
  <p>Some user clicks on the button with the <code>label</code> <em>test</em></p>
  
  <pre><code>&gt; c
  &gt; TRUE
  </code></pre>