Python / Git / Module structure best practice

Question

We have a lot small projects that share common utility "projects"

Example :
utility project math contains function add
project A and project B both need math.add
project A has nothing to do with project B

so is it a good idea to have 3 git repositories (project_A,project_B and math) and clone them locally as

/SOMWHERE/workspace/project_A
/SOMWHERE/workspace/math

and have in /SOMWHERE/workspace/project_A/__init__.py something like

import sys
sys.path.append('../math')
import math

math.add()

I have read Structuring Your Project but that doesn't handle SCM and sharing modules.

So to sum up my question: is

sys.path.append('../math')    
import math

good practice or is there a more "pythonic" way of doing that?

Answer 1

Submodules are a suboptimal way of sharing modules like you said in your comments. A better way would be to use the tools offered by your language of choice, ie Python.

First, create virtualenvs to isolate every project python environment. Use pip to install packages and store dependencies in a requirements.txt file.

Then, you can create a specific package for each of your utils library using distutils and share it on Pypi .

If you don't want to release your packages into the wild, you can also host your own Pypi server .

Using this setup, you will be able to use different versions of your libraries and work on them without breaking compatibility with older code bases. You will also avoid using submodules, that are difficult to use with git.

Answer 2

all of what you describe (3 projects) sounds fine except that you shouldn't mess around with sys.path . instead, set the PYTHONPATH environment variable.

also, if you were not aware of distutils i am guessing you may be new to python development, and may not know about virtualenv. you should use that too (it allows you to develope against a "clean" python version that has no packages, or only the packages you install for that env).