title: Linking main.py with .kv file
body: <p>I am trying to get a label which has text of string stored in <code>w</code> variable in my <code>main.py</code> file and label is in <code>.kv file</code> let me show you both files.</p>
  
  <p>Here's main.py file</p>
  
  <pre><code>from kivy.app import App
  from kivy.properties import StringProperty
  
  class ExampleApp(App):  
      def hell(self):
          w="hello world"
      def build(self):
          self.load_kv("exapmleapp.kv")
  
  if __name__ == "__main__":
      ExampleApp().run()
  </code></pre>
  
  <p>And here is my <code>.kv</code> file.</p>
  
  <pre><code>Label:
      text:app.w
  </code></pre>
  
  <p>Every time when I run my main.py file, it gives me this error.</p>
  
  <blockquote>
    <p>1:
     2:Label:
     3:   text:app.w  ...  AttributeError: 'ExampleApp' object has no attribute 'w'    File
    "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1649, in
    create_handler
         return eval(value, idmap)    File "./exampleapp.kv", line 3, in 
         text:app.w    File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 858, in
    <strong>getattribute</strong>
         return getattr(object.<strong>getattribute</strong>(self, '_obj'), name)
         File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 2011, in _apply_rule
         value, rule, rctx['ids'])    File "/usr/local/lib/python2.7/dist-packages/kivy/lang.py", line 1654, in
    create_handler
         cause=tb)</p>
  </blockquote>
  
  <p>How can I get the label that has text stored in w variable in my main.py file</p>