title: A filter that only runs once?
body: <p>I made a filter that replaces a key with a translation.</p>
  
  <pre><code>&lt;label&gt;{{'city' | translate}}&lt;/label&gt;
  </code></pre>
  
  <p>The filter simply looks up the key <code>city</code> in a json file and returns the value.</p>
  
  <p>What I didn't realize is that filters are run... a lot. After some research I see that there are better ways to do this but I am not willing to do a complete refactor.</p>
  
  <p>How can I simply tell this filter to only run once per key.</p>
  
  <p>As a workaround, I am pre-compiling the templates and replacing calls to <code>translate</code> with the correct string. This works for most cases but there are places where the key is dynamic or the translation is a function that takes scope variable as arguments</p>
  
  <pre><code>&lt;label&gt;{{'greeting' | translate:firstName:lastName}}&lt;/label&gt;
  </code></pre>
  
  <p>I want Angular to just do a one-time replace of these and never think about it again.</p>