title: Accessing class instance from another module (Python)
body: <p>I'm pretty new to Python as to OOP in general which is probably be the reason that I can't figure out the following:<br>
  I'm writing a python script which opens a text file and subsequently translates it into HTML, maintaining it's "own" mirrored directory-trees for the edit files and the html files. 
  Since directory creation and deletion is done automatically depending on, among other criteria, whether the file existed before or not, I need some kind of automatic and dynamic path adjustment. The script has to do several checks for files and associated directories before it can set the corresponding paths and start the processing.  </p>
  
  <p>I decided to put most of the more general functions (check file existence, show dialogs for duplicate filenames if found, etc) in a separate module, since they are quite specific and not depending on any state. Actually they create the state (path variables), so a class would not make sense if this is not a misconception. </p>
  
  <p>On the other hand I'm using a class for the pure getting and setting the paths since I need the paths accessible from every module, so it's basically a global access point for paths.
  This class is instantiated in the main module.</p>
  
  <p>Now my problem is that I can't figure out how to manipulate the paths (using the path
  setters) of that instance in the main module from a function inside the tools module. Importing the class instance or the main module into the tools module doesn't seem to work.</p>
  
  <p>Generally speaking, is it possible to use a class instance across all module files and is this the way to go, or am I missing the point somehow?</p>
  
  <p>I paste the relevant bits of code for illustration:</p>
  
  <p>Setter/Getter class inside the main module</p>
  
  <pre><code>class SetEnv():
  def __init__(self):
      pass
  
  def set_path_srcfile(self, path_srcfile):
      self.path_srcfile = path_srcfile 
  
  def set_path_htmlfile(self):
      self.path_htmlfile = self.path_srcfile.replace('source', 'html', 1).replace('.txt', '.html', 1)
  
  def get_path_srcfile(self):
      return self.path_srcfile
  
  def get_path_htmlfile(self):
      return self.path_htmlfile
  </code></pre>
  
  <p>Later in main_module:</p>
  
  <pre><code>env = SetEnv()
  </code></pre>
  
  <p>Part of tools module (inside a def acting upon user input):</p>
  
  <pre><code>import main_module as mm
  path_srcfile = dict[int(user_option)][1] # dictionary holding the path we want to set
  mm.env.set_path_srcfile(path_srcfile)
  mm.env.set_path_htmlfile()
  </code></pre>