DOC: Add an explanation of how to set up a namespace package
+"""
+The PyBIDS extension namespace package
+
+``bids.ext`` is reserved as a namespace for extensions to install into.
+To write such an extension, the following things are needed:
+
+1) Create a new package with the following structure (assuming setuptools)::
+
+ package/
+ bids/
+ ext/
+ __init__.py
+ EXTENSION/
+ __init__.py
+ ...
+ setup.cfg
+ setup.py
+
+ The important things to note are that the ``bids/`` directory must be
+ empty apart from ``ext/`` and ``bids/ext/`` must be empty except for
+ your extension and an ``__init__.py``.
+
+2) Place the following (and nothing else) in ``__init__.py``::
+
+ __path__ = __import__('pkgutil').extend_path(__path__, __name__)
+
+3) Include the following lines in ``setup.cfg``::
+
+ [options]
+ install_requires =
+ pybids >= 0.15
+ packages = find_namespace:
+
+ [options.packages.find]
+ include =
+ bids.ext.EXTENSION
+ bids.ext.EXTENSION.*
+
+"""
+
__path__ = __import__('pkgutil').extend_path(__path__, __name__)
