Detect the Python distribution specification/format

distribution_specification.py

def _get_dist_spec(dist):
    """Returns the specification used by the distribution.

    The result is "dist-info", "egg-info", "egg" or "distutils-legacy".
    """

    def is_dir():
        return dist.path is not None and os.path.isdir(dist.path)

    def is_file():
        return dist.path is not None and os.path.isfile(dist.path)

    # Comments and detection has been adapted from
    # https://github.com/pypa/pip/blob/a15dd75/src/pip/_internal/metadata/base.py#L219
    spec = "unknown"
    if is_dir() and dist.path.endswith(".dist-info"):
        # This distribution was installed with the "modern format".
        #
        # This applies to installations made by setuptools
        # (but through pip, not directly), or anything using the
        # standardized build backend interface (PEP 517).
        spec = "dist-info"
    elif is_dir() and dist.path.endswith(".egg-info"):
        # This distribution was installed with the .egg-info format.
        #
        # This usually indicates the distribution was installed with
        # setuptools with an old pip version or with
        # single-version-externally-managed.
        spec = "egg-info"
    elif dist.path.endswith(".egg"):
        # This distribution was installed as an egg.
        #
        # This usually indicates the distribution was installed by
        # (older versions of) easy_install.
        #
        # Deprecated, but pip still support it.
        spec = "egg"
    elif is_file():
        # This distribution was installed with legacy distutils format.
        #
        # A distribution installed with "raw" distutils not patched by setuptools
        # uses one single file.
        #
        # Deprecated, but pip still supports it.
        spec = "distutils-legacy"

    return spec