Get a git description of a package

git-describe.py

# Put this anywhere within the package then call it at runtime to get a git description
# of the package version being used.  This only works when the package is being imported
# from a directory checked out directly from github, which is generally not the case
# for pip- or conda-installed packages.

def git_describe():
    """Return a string describing the git origin of the package where this function is defined.

    The result is usually <tag>-<n>-g<hash> where <tag> is the last tag, <n> is the number of
    subsequent commits, and <hash> is the current git hash.  When n=0, only <hash> is returned.
    Details on git-describe are at https://git-scm.com/docs/git-describe
    """
    try:
        path = pathlib.Path(__file__).parent
        process = subprocess.Popen(
            ['git', 'describe', '--tags', '--always'],
            cwd=path, shell=False, stdout=subprocess.PIPE)
        return process.communicate()[0].strip().decode()
    except Exception as e:
        return None