Some improvements

[xowenx]

change --python_out to packagedir,
add --proto_path/-I option,
add some hint when not need generating pb2 file.

[pupssman]

Hi there! Thanks for PR!

But I've got some concerns, particularly about the --python_out thing. My own test example has directory structure as follows:

my_package/setup.py
my_package/my_pack/__init__.py
my_package/my_pack/my.proto

And when I run python setup.py build_proto it places my_pb2.py in the my_pack dir if and only if I specify --python_out=.. If I use --python_out=<packagedir> it places generated file here:

my_package/my_pack/my_pack/my_bp2.py

If that behaviour is not true for you, please specify setuptools version and protoc versions, mine are:
root@home: ~/ protoc --version libprotoc 2.5.0
and

>>> import setuptools as s
>>> s.__version__
'3.6'
>>> 

[mavlyutov]

soooo outdated

95:~ mavlyutov$ python
Python 2.7.6 (default, Sep  9 2014, 15:04:36)
[GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.39)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import setuptools as s
>>> s.__version__
'15.0'

[xowenx]

My version combination is (setuptools 15.0/ protoc 2.6.1).

In my situation, protoc command will run at the same dir hierarchy as setup.py, and if --python_out be set as "." , it would generate pb2.py file at the package root dir.

I'm curious why protoc generate redundancy dir at in your description, maybe relate to protoc version ?