Library import structure in python

Question

I am developing a library in python3x and I'm having some trouble trying to import all modules, classes and functions.

    /example.py
    /math/
        __init__.py
        linalg.py
             solve() #inside module.py

The issue here is that I would like to simply be able to import my library inside example.py and then use all functions defined inside the different modules as numpy does, for example:

import math as m

m.solve()

instead of using

import math as m
m.linalg.solve()

or

import math.linalg as m
m.solve()

How should I define __init__.py to include everything this way. I've tried using dir(linalg), absolute imports, etc by I can't get my head around it.

Thx.

SOLUTION:

At the end what I did was create a wrapping layer inbetween to hide the module dependency.

Inside the __init__.py:

from .linalg import *
from .wrappers import *

then created a wrappers.py along with linalg.py:

from math.linalg import solve

def wrapper_solver():
{
solve()
}

and then in example.py:

import math as m

m.wrapper_solver()

Hope it helps someone.

Answer 1

Two solutions :

1. Either import the whole path to your linalg.py :

example.py :

#!/usr/bin/env python3                                                         

import math.linalg as m # rather than just `import math`.

m.solve()

2. Either make solve available directly from math with your __init__.py :

math/__init__.py :

from linalg import solve

---

Edit :

You could modify your python path as Muhammed Ajwahir suggested. But in my humble opinion that doesn't solve the problem. It's a matter of import path. The root directory is added by default to the Python path (when executing ./example.py). That's enough to import everything in sub directories. I think there is no need to modify the path.

Edit 2:

If you want to import everything in your __init__.py you can also use from math import * (which is considered as a bad practice). Or add everything by hand in your __init__.py.

But in your case you might consider refactoring your tree in just :

.
|-- example.py
|-- math.py

And forget the math directory structure. This way a simple import math should be enough.

I'd also like to point out that math is already an existing library in Python. I think you should consider renaming it to avoid name conflict.

Answer 2

In your linalg.py write __ all __ write all the function you want to expose to the package.
example __ all __ =['solve']

Then in __ init __.py ( module where linalg.py file is present ) file write from .linalg import * this will import all function defined in __ all __ (note function name should be unique) . and then in __ init __.py write __ all __ = linalg.__ all __ ( use + if there are more file ie __ all __ = linalg.__ all __ +file2.__ all __ .

and then in the example, you can call solve as from math import solve.

Answer 3

If you want to add something inside a folder you have to add that folder in the system directory. you can do that by -

import sys
sys.path.insert(0, '/path/to/math/folder')

import linalg as m

m.solve()

EDIT 1:

OR

In __init__.py, add

__all__ = ["linalg", "foo", "barr"]

etc, and import math as m in your main script hope that helps.