title: Accessing a Python global variable across files
body: <p>I have three python files in a project:</p>
  
  <pre><code>'''lib.py
     library file that first defines and also accesses a boolean flag'''
  vflag = False
  ...
  def lib_method()
    global vflag
    if not vflag:
      do_something_here
  
  '''app.py
     main application that sets the boolean flag defined in lib.py'''
  import lib
  lib.vflag = method_that_sets_or_resets_vflag()
  
  
  '''processor.py
     does some processing and needs to access the bool flag'''
  from lib import *
  ...
  def processor_method()
    global vflag
    ...
    if vflag:
      do_something_here
  </code></pre>
  
  <p>I am able to set/ reset the flag at app.py, but processor method is not able to get the correct value for this boolean variable.</p>
  
  <p>It only gets whatever is set at the beginning of lib.py(not what is set by app.py). The requirement is to access the value set at runtime by app.py, NOT the value to which it was initialized by lib.py</p>
  
  <p>I am importing the lib file in different ways at app.py and processor.py. Does that make a difference ?</p>
  
  <p>It may be a fundamental mistake, so I will appreciate if some one can point me to a specific knowledge base.
  Also, it is messing with my understanding of global variables. If I define a variable to be 'global', does that mean the variable stays to be a global variable in all the files that import this variable(or the file containing the variable definition)</p>