正确设计Python项目

Question

I'm planning to have project with following structure:

./runme.py
./my_modules/__init__.py
./my_modules/global_imports.py
./my_modules/user_defined_functions.py

Idea is to store important variables in global_imports.py from where they will be imported into runme.py using from my_modules.global_imports import * (I know it is a bad practice import modules this way, but I promise there will be just few variables with not colliding names)

Four questions:

1. Two of the variables contained inside global_imports.py should be SCRIPT_PATH and SCRIPT_DIR . I've tried SCRIPT_PATH = os.path.realpath(__file__) and SCRIPT_DIR = os.path.dirname(SCRIPT_PATH) but it returns path (directory) for global_imports.py not for runme.py . How can I get path (directory) of runme.py ?

2. Inside global_imports.py I will probably import modules such as os and sys . I also need to import those modules inside runme.py . Is this considered as problem, when modules are imported first from another module and later from main script or vice versa?

3. Is it possible to import variables from global_imports.py into user_defined_functions.py ? I consider this as bad practice I'm just curious.

4. Is there better approach to separate project into modules?

Answer 1

Addressing your questions in order:

1. In the first variable SCRIPT_DIR you are getting the full path of the file global_imports.py, which would be something like this:

    SCRIPT_PATH = '/home/../../my_project/my_modules/global_imports.py' 

   now in order to get the directory of runme.py, we should consider another variable:

    SCRIPT_PATH_DIR = os.path.dirname(SCRIPT_PATH) 

   this will give us the path

    SCRIPT_PATH_DIR = '/home/../../my_project/my_modules/' 

   now to get to its parent directory which contains runme.py we can get like this:

    SCRIPT_DIR = os.path.abspath(os.path.join(SCRIPT_PATH_DIR, os.pardir)) 

   Now, SCRIPT_DIR gives the path of runme.py ie:

    SCRIPT_DIR = '/home/../../my_project/' 

2. As per our project structure, runme.py should only conrtain an import to the main module and then command to run the app. So, it shouldn't contain any other imports. Still if you need to use a module then explicitly import it in the runme.py as one of the Zen of Python says 'Explicit is better than implicit'

3. Yes, it is possible, you can do it like this:

    from .global_imports import variable_name 

   but in general you should have a separate config.py or settings.py file in '/../my_project/' directory which should contain all the settings and variables which you may need to use anywhere in the project.

4. This approach is good enough as far as I've seen. Your main project directory contains runme.py and other modules which are used inside the project. 'my_modules' is one of the modules I think. You can have more of such modules inside the project directory. A better approach is to have settings and configurations inside one of the modules(such as my_modules) only and to have other modules for the functionality.

Hope this helps, please comment if something is unclear.