Split a large python file into a module with shared dependencies

Question

When developing in Flask, I would like to put all my models, controllers ... in their own separate file. Thus, I do not need to look for any controller, model in a large file; he keeps everything clean. It might look like this:

/controllers __init__.py login.py logout.py profile.py 

All of these files have (almost) the same dependencies. I do not want to add all the dependencies to each file again and again. One solution I came up with is to use the depencies.py file, which imports all the dependencies, which I then include in each individual file.

  /controllers __init__.py dependencies.py (all the imports) login.py (import dependencies.py) logout.py (import dependencies.py) profile.py (import dependencies.py) 

However, this is not a very elegant solution. I wonder if it is possible to do something like __init__.py , which has dependencies on top and then “includes” individual files and that everything is done in this way, so that you actually do not need to include common dependencies in each file.

An example of what I would like to do (does not work):

 #common dependencies from app import mail from flask import session ... #actual models (which depend on these dependencies) from user import User from code import Code from role import Role 

Answer 1

Import files individually

Import only the necessary dependencies in each or your files. If profile needed only by flask , import only this into the file. If login.py requires flask and app , import both into this file. If the __init__.py code does not actually use a third-party 3 ^rd module, you do not need to import it there. Depending on how you end up using your package, you can set the __all__ list with your modules in __init__.py .

Literature:

• Import only ever loads a module once. Any import after that just adds it to the current namespace.
  - another answer

• For efficiency reasons, each module is imported only once per interpreter session.
  - python docs

• __all__ explanation