Why python finds module instead of package if they have the same name?

Question

Here is my directory structure:

/home/dmugtasimov/tmp/name-res
    root
        tests
            __init__.py
            test_1.py
        __init__.py
              


        

Answer 1

I simplified the example from the question to demostrate that only four solutions are possible:

• Explicit relative import from . import some_module or with more commas from ..
• Relative import (without "xyz." if used in the package "xyz")
• Absolute import using from __future__ import absolute_import (or use Python 3)
• Never repeat the top level importable name of the package in any path inside it.

What solution is the best? It depends on personal preference of Python 2 or 3. Only the last one is nice and universal for all Pythons. It was really a useful question.

---

xyz/tests/__init__.py: import xyz.tests.t

xyz/tests/t.py:

import sys
print('sys.path = %s' % sys.path) # see that the parent of "xyz" is on sys.path
print("importing xyz.tests")
import xyz.a

xyz/a.py:

# solution A: absolute_import by __future__  (or use Python 3)
#from __future__ import absolute_import
print("importing xyz.a")
# solution B: explicit relative import
#from . import b    # and remove "import xyz.b"
# solution C: relative import (not recommended)
#import b           # and remove "import xyz.b"
import xyz.b

xyz/b.py: print("imported xyz.b")

xyz/xyz.py: print("Imported xyz.xyz !!!")

xyz/__init__.py: empty file

---

Everything possible fails, e.g.

parent_of_xyz=...  # The parent directory of "xyz" - absolute path
cd $parent_of_xyz
python -m xyz.tests.t
PYTHONPATH=$parent_of_xyz/xyz python -m unittest tests
PYTHONPATH=$parent_of_xyz     python xyz/tests/t.py

with messages like

Imported xyz.xyz  !!!
...
ImportError...

If any solution is applied (uncommented), all three examples work.

It can be more simplified without using any subdirectory.

EDIT: I tried yesterday many tests but I wrote it inconsitently from different versions. Excuse me that it was unreproducible from the answer. Now it is fixed.