RFC 17: Python Namespaces

Author: Howard Butler
Contact: hobu.inc@…
Status: Adopted

Summary

GDAL bindings for Python have historically dodged the normal Python practices of using packages and namespaces to provide organization. This RFC implements a new namespace for Python, called osgeo, where the GDAL Python bindings henceforth will reside. Backward compatibility is provided, so that current code will continue to run unchanged, but new developments should utilize the namespace for code organization and global namespace pollution reasons. As of 10/1/2007, the changes described here in RFC 17 only pertain to the "next-gen" Python bindings. It is expected that these bindings will be the default bindings for GDAL 1.5.

Objective

To provide the GDAL Python bindings in a Python package that is properly namespaced, eliminating pollution of Python's global namespace.

Past Usage

GDAL's Python bindings previously used globally-aware Python modules:

import gdal
import osr
import ogr
import gdalconst
import gdalnumeric

New Usage

RFC 17 now provides these modules under the osgeo namespace:

from osgeo import gdal
from osgeo import osr
from osgeo import ogr
from osgeo import gdalconst
from osgeo import gdal_array

Additionally, the old module-style imports continue to work with a deprecation warning:

>>> import gdal
/Users/hobu/svn/gdal/swig/python/gdal.py:3: DeprecationWarning: gdal.py was placed in a namespace, it is now available as osgeo.gdal
  warn('gdal.py was placed in a namespace, it is now available as osgeo.gdal', DeprecationWarning)

It is planned that we will remove the GDAL-specific global modules at some point in the future.

Other Sprint Updates

The work for this RFC was done at the FOSS4G2007 GDAL code sprint by Howard Butler and Chris Barker. In addition to the Python namespacing, some minor issues were dealt with respect to building the GDAL bindings.

1. The next-gen Python bindings now use setuptools by default if it is available.
2. The ./swig/python directory was slightly reorganized to separate extension building from pure python modules.
3. gdal2tiles, a Google Summer of Code project by Petr Klokan, was integrated into the next-gen bindings

Voting History

A voice vote (our first ever!) commenced at the FOSS4G2007 sprint.

• Frank Warmerdam +1
• Howard Butler +1
• Daniel Morissette +1
• Tamas Szekerest +1