[protobuf] Using Python protobuf library without setuptools?

[Nick Carter]

My project pulls the protobuf source directly from code.google.com, and builds the tools and libs (protoc, libprotobuf, libprotobuf-lite) as part of its build process.  But now I want to use protos from Python, and I'm having trouble getting the python protobuf library to import properly from the generated _pb2.py code.

Protobuf's python/ directory is in my PYTHONPATH, but my standalone python build chokes on the python/google/__init__.py:

__import__('pkg_resources').declare_namespace(__name__)

because the hermetic python used by my build doesn't have setuptools.  Simply removing that line (or adding a try/except for ImportError) seems to make things to work for me.

Do I really need to pull in setuptools, in order to use python protobufs?  Or is there a way to make the pkgresources dependency optional?

 - nick

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[Kenton Varda]

The purpose of that line is to declare that the "google" package is just a namespace, so that other google projects (like AppEngine) can also place their code under "google".  In retrospect, we probably should have just created a top-level "protobuf" package.

If you make sure that all packages that you are using under "google" are part of one big source tree, then the line is unnecessary -- it is only needed when the "google" package might appear in multiple locations in your python path.  So if this is the case for you, you can simply replace that __init__.py with an empty file.