title: Python: Best practice for including a version number in an app?
body: <p>I have a PyQt application that reads and writes data files. I am including a 'version number' in each file written.  This is a simple number similar to: 1.2  or something (major and minor versions).</p>
  
  <p>I am doing this so that I can change the format of these data files in future versions and then still correctly parse them simply by checking to see what the version is inside the file.</p>
  
  <p>My question is what is the best practice for keeping this number stored inside the app itself.  I.e. do I just hard-code the app version number into the class that is responsible for reading and writing files?  Or should I have some sort of object/variable stored at the top-level of the app and somehow access it from the class responsible for reading and writing these files.  If the latter, how do I store it and how do I access it?</p>
  
  <p>Thanks.</p>