Post version bumping setuptools-scm version-scheme callable

post_version_scheme.py

import setuptools_scm
from packaging.version import Version


def post_bump_then_dev(version: setuptools_scm.ScmVersion) -> str:
    """
    Ahead of tag:
      - v0.1          -> 0.1.post1.devN
      - v0.1.post1    -> 0.1.post2.devN
    Exact tag:
      - v0.1.post1 at HEAD -> 0.1.post1
    Local part (+gSHA / timestamp) is handled by local_scheme.
    """
    # If exactly on the tag (and clean), keep the tag version verbatim.
    if version.distance == 0 and not version.dirty:
        return str(version.tag)

    tag_v = Version(str(version.tag))

    # Base release like "0.1" or "1.2.3"
    base = ".".join(map(str, tag_v.release))

    # Any prerelease
    pre = tag_v.pre and "".join(map(str, tag_v.pre))

    # Any epoch
    epoch = f"{e}!" if (e := tag_v.epoch) else ""

    # Bump post: None->1, N->N+1
    next_post = (tag_v.post or 0) + 1

    # Use the actual commit distance from the tag for devN
    return f"{epoch}{base}{pre}.post{next_post}.dev{version.distance}"


if __name__ == "__main__":
    print(
        setuptools_scm.get_version(
            version_scheme=post_bump_then_dev,
            local_scheme="node-and-timestamp",
            tag_regex=r"^v(?P<version>(\d+!)?\d+\.\d+.*)$",
        )
    )