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Namespace Packages

The owi-metadatabase-shm package extends the owi.metadatabase namespace using PEP 420 implicit namespace packages.

How It Works

The src/owi/metadatabase/__init__.py file uses pkgutil.extend_path to allow multiple installed packages to contribute modules under the same owi.metadatabase prefix:

from pkgutil import extend_path
__path__ = extend_path(__path__, __name__)

This means the core SDK (owi-metadatabase) and this extension can both install modules under owi.metadatabase without conflicting.

Validation

import owi.metadatabase
# The namespace package has no __file__ attribute.
assert not hasattr(owi.metadatabase, "__file__")

After installing the extension:

import owi.metadatabase.shm
print(owi.metadatabase.shm.__name__)
# → "owi.metadatabase.shm"

Practical Implications

  • No __init__.py ownership conflicts — each extension package contributes its own sub-namespace.
  • Install order does not matter — pkgutil.extend_path merges all installed contributions at import time.
  • Uninstalling one extension does not break others living under the same namespace.