title: Swift Error: Variable used within its own initial value
body: <p>When I'm initializing an instance of an entity I'm getting the error <code>Variable used within its own initial value</code>.</p>
  
  <p>Here is the code throwing the error:</p>
  
  <pre><code>class func buildWordDefinition (word:String, language:Language, root:TBXMLElement) -&gt; WordDefinition
      {
          let word = WordDefinition(word: word, language: language)
  </code></pre>
  
  <p>The error points at the <code>word</code> variable. </p>
  
  <p>Here is the WordDefinition class:</p>
  
  <pre><code>class WordDefinition {
      let word: String
      let language: Language
  
      init(word: String, language:Language)
      {
          self.word = word
          self.language = language
      }
  }
  </code></pre>
  
  <p>What does this error mean ?</p>