title: Get the thread state stated from another class
body: <p>Let's say I have the following code (<code>start.py</code>) that starts a thread and never exits (Note: don't mind the typos or lack of some code lines, just get the idea.):</p>
  
  <pre><code>from threading import Thread
  from anApp import AnApp
  
  class ClassA(Thread):
      def __init__(self, _parent):
          Thread.__init__(self)
          self.parent = _parent
  
      def run(self):
          while 1:
              self.parent.anApp.execute()
  
              # Here, I want to known if the thread started in appX.py is alive.
              # if the thread stated by appX.py is alive:
              #     print 'App x is running'
              # else:
              #     print 'App x is not running'
  
  class App():
      def __init__(self):
          self.th = None
          self.anApp = AnApp()
  
      def someFunction(self):
          self.th = ClassA(self)
          self.th.start()
  </code></pre>
  
  <p>Now, <code>anApp.py</code> looks something like this:</p>
  
  <pre><code>from appX import App
  
  Class AnApp():
      # def __init__(self) goes here...
  
      def execute(self):
          self.appX = App()
          self.appX.startRunning()
  </code></pre>
  
  <p>Finally, <code>appX.py</code> looka something like this (similar to <code>start.py</code>):</p>
  
  <pre><code>from threading import Thread
  
  class ClassX(Thread):
      def __init__(self, _parent):
          Thread.__init__(self)
          self.parent = _parent
  
      def run(self):
          while 1:
              print 'Im here!!!'
  
  class App():
      # def __init__(self) goes here....
  
      def startRunning(self):
          self.listen = ClassX(self)
          self.listen.start()
  </code></pre>
  
  <p>I want to know if the thread started by <code>startRunning</code> in <code>appX.py</code> is alive, in <code>start.py</code> (check the comments I wrote above).</p>