Get pip/setuptools version of package from within the package?

Question

I have a package using setuptools for it's deployment. I want to have a function within the package (CLI tool) which reports the version of the package. This should report the version field used in the call to setup. Is there a way I can access this value on the installed package?

For example, my setup.py calls setup with version = '0.1.6' and also installes a command line tool tool. I want that a call to tool --version prints the version 0.1.6.

Answer 1

It's often common practice to list this in your package's main __init__.py file. For instance, if you package was called sample, and lived in the sample directory, you would have a sample/__init__.py file with something like this:

__version__ = '0.1.6'

def version():
    return __version__

And make use of that however you want in your CLI interface.

In your setup.py, if you wish you can read this value from your code in order not to create redundancy, something like this:

import os.path

here = os.path.abspath(os.path.dirname(__file__))

# Read the version number from a source file.
# Why read it, and not import?
# see https://groups.google.com/d/topic/pypa-dev/0PkjVpcxTzQ/discussion
def find_version(*file_paths):
    # Open in Latin-1 so that we avoid encoding errors.
    # Use codecs.open for Python 2 compatibility
    with codecs.open(os.path.join(here, *file_paths), 'r', 'latin1') as f:
        version_file = f.read()

    # The version line must have the form
    # __version__ = 'ver'
    version_match = re.search(r"^__version__ = ['\"]([^'\"]*)['\"]",
                              version_file, re.M)
    if version_match:
        return version_match.group(1)
    raise RuntimeError("Unable to find version string.")

setup(
    name="sample",
    version=find_version('sample', '__init__.py'),
    # ... etc

For lots more discussion on different ways to implementing this sort of goal, please check http://packaging.python.org/en/latest/tutorial.html#version