Question

What is the standard way of declaring configuration variables for your program at the top of a python script? These are used throughout the program in multiple classes and functions. Is the best way:

1. To create a mixed dictionary with the configuration options, and pass these to any classes that need them. Downside: this requires passing extra attributes. For example:

   config = {'parseTags': {'title','font','p'},    
       'name': 'steve',                
       'logFrequencies': 10,               
       'print_rate': False  
       }
   

    

   newCustomObject = CustomClass(config)
   customfunction(config)
   print 'hi',config['name']
   

2. Create global variables at the beginning of the file and call those throughout the program. Downside: ruins the encapsulation of the classes.

3. Something else.

What is the most pythonic way of doing this?

Answer 1

For constants used in a single file (module), I usually just declare global variables at the top. This does not lose encapsulation in any meaningful way (it’s no different from putting those constants in a base class that every class inherits from).

The django config system provides a nice way to create shared constants: you create a module, and the config system creates a read-only object from it, exposing the members of the module.