title: Use dynamic rules with Vue Validator
body: <p>I'm using Vue.js with Vue Validator and I'm trying to implement some dynamic validation. By this I mean the set of rules for a particular form field may change as a result of the rule being bound to a dynamic or computed variable. This is what I mean:</p>
  
  <pre><code>&lt;input v-validate:field="someDynamicRule"&gt;
  </code></pre>
  
  <p>and in my Vue component the value of <code>someDynamicRule</code> can change:</p>
  
  <pre><code>//...
  computed: {
    someDynamicRule () {
      return this.someBool ? ['required'] : []
    }
  }
  //...
  </code></pre>
  
  <p>However, this doesn't work; the validation rule is stuck with what it was when the component is first loaded. Here is a fiddle demonstrating this behaviour:</p>
  
  <p><a href="http://jsbin.com/furepirowi/edit?html,js,output" rel="nofollow">http://jsbin.com/furepirowi/edit?html,js,output</a></p>
  
  <p>Is there a way to have the validator react to changes to the rules set on the fields?</p>