title: Kivy - Accessing id of widget outside of the root class
body: <p>I wish to retrieve the id of a widget in order to access its <code>text</code> attribute, in a widget class <em>outside</em> of the root class. I understand in order to affect or retrieve items with an id from kv-lang, the following syntax may be used:</p>
  
  <pre><code>self.ids.some_id.some_attribute = new_value
  </code></pre>
  
  <p>This works perfectly fine when used in the root class, as access is available to all its children. However in a widget class, the class only refers to the widget declared, so any ids outside of it are out of scope.</p>
  
  <pre><code>&lt;Root&gt;:
      ...
          SomeButton:
             ...
          TextInput:
              id: some_id
  </code></pre>
  
  <p>What doesn't work:</p>
  
  <pre><code>class SomeButton(Button):
      def on_press(self):
          print(self.ids.some_id.text)
  </code></pre>
  
  <p>As I mentioned, this is understandable. But I don't know then what is used in this instance. Any assistance would be appreciated :)</p>