Source code for plaster.loaders

try:
    from importlib import metadata
except ImportError:  # pragma: no cover < py38
    import importlib_metadata as metadata

from .exceptions import LoaderNotFound, MultipleLoadersFound
from .interfaces import ILoaderInfo
from .uri import parse_uri


def get_sections(config_uri):
    """
    Load the list of named sections.

    .. code-block:: python

        sections = plaster.get_sections('development.ini')
        full_config = {
            section: plaster.get_settings('development.ini', section)
            for section in sections
        }

    :param config_uri: Anything that can be parsed by
        :func:`plaster.parse_uri`.

    :returns: A list of section names in the config file.

    """
    loader = get_loader(config_uri)

    return loader.get_sections()


[docs]def get_settings(config_uri, section=None, defaults=None): """ Load the settings from a named section. .. code-block:: python settings = plaster.get_settings(...) print(settings['foo']) :param config_uri: Anything that can be parsed by :func:`plaster.parse_uri`. :param section: The name of the section in the config file. If this is ``None`` then it is up to the loader to determine a sensible default usually derived from the fragment in the ``path#name`` syntax of the ``config_uri``. :param defaults: A ``dict`` of default values used to populate the settings and support variable interpolation. Any values in ``defaults`` may be overridden by the loader prior to returning the final configuration dictionary. :returns: A ``dict`` of settings. This should return a dictionary object even if no data is available. """ loader = get_loader(config_uri) return loader.get_settings(section, defaults)
[docs]def setup_logging(config_uri, defaults=None): """ Execute the logging configuration defined in the config file. This function should, at least, configure the Python standard logging module. However, it may also be used to configure any other logging subsystems that serve a similar purpose. :param config_uri: Anything that can be parsed by :func:`plaster.parse_uri`. :param defaults: A ``dict`` of default values used to populate the settings and support variable interpolation. Any values in ``defaults`` may be overridden by the loader prior to returning the final configuration dictionary. """ loader = get_loader(config_uri) return loader.setup_logging(defaults)
[docs]def get_loader(config_uri, protocols=None): """ Find a :class:`plaster.ILoader` object capable of handling ``config_uri``. :param config_uri: Anything that can be parsed by :func:`plaster.parse_uri`. :param protocols: Zero or more :term:`loader protocol` identifiers that the loader must implement to match the desired ``config_uri``. :returns: A :class:`plaster.ILoader` object. :raises plaster.LoaderNotFound: If no loader could be found. :raises plaster.MultipleLoadersFound: If multiple loaders match the requested criteria. If this happens, you can disambiguate the lookup by appending the package name to the scheme for the loader you wish to use. For example if ``ini`` is ambiguous then specify ``ini+myapp`` to use the ini loader from the ``myapp`` package. """ config_uri = parse_uri(config_uri) requested_scheme = config_uri.scheme matched_loaders = find_loaders(requested_scheme, protocols=protocols) if len(matched_loaders) < 1: raise LoaderNotFound(requested_scheme, protocols=protocols) if len(matched_loaders) > 1: raise MultipleLoadersFound( requested_scheme, matched_loaders, protocols=protocols ) loader_info = matched_loaders[0] loader = loader_info.load(config_uri) return loader
[docs]def find_loaders(scheme, protocols=None): """ Find all loaders that match the requested scheme and protocols. :param scheme: Any valid scheme. Examples would be something like ``ini`` or ``pastedeploy+ini``. :param protocols: Zero or more :term:`loader protocol` identifiers that the loader must implement. If ``None`` then only generic loaders will be returned. :returns: A list containing zero or more :class:`plaster.ILoaderInfo` objects. """ # build a list of all required entry points matching_groups = ["plaster.loader_factory"] if protocols: matching_groups += [f"plaster.{proto}_loader_factory" for proto in protocols] scheme = scheme.lower() # if a distribution is specified then it overrides the default search parts = scheme.split("+", 1) if len(parts) == 2: try: dist = metadata.distribution(parts[0]) except metadata.PackageNotFoundError: pass else: ep = _find_ep_in_dist(dist, parts[1], matching_groups) # if we got one or more loaders from a specific distribution # then they override everything else so we'll just return them if ep: return [EntryPointLoaderInfo(dist, ep, protocols)] return [ EntryPointLoaderInfo(dist, ep, protocols=protocols) for (dist, ep) in _iter_ep_in_dists(scheme, matching_groups) ]
def _iter_ep_in_dists(scheme, groups): # XXX this is a hack to deduplicate distributions because importlib.metadata # does not do this for us by default, at least up to Python 3.11. # Specifically, if ``lib`` is symlinked to ``lib64`` then a Distribution # object will be returned for each path, causing duplicate entry points # to be found. # # See https://github.com/Pylons/plaster/issues/25 dups = set() for dist in metadata.distributions(): name = dist.metadata["Name"] if name in dups: # pragma: no cover continue dups.add(name) ep = _find_ep_in_dist(dist, scheme, groups) if ep: yield (dist, ep) def _find_ep_in_dist(dist, scheme, groups): entry_points = [ entry_point for entry_point in dist.entry_points if entry_point.group in groups and (scheme is None or scheme == entry_point.name.lower()) ] # verify that the entry point from each group points to the same factory if len({ep.value for ep in entry_points}) == 1: return entry_points[0] class EntryPointLoaderInfo(ILoaderInfo): def __init__(self, dist, ep, protocols=None): self.entry_point = ep self.scheme = "{}+{}".format( dist.metadata["name"] if "name" in dist.metadata else "Unknown", ep.name ) self.protocols = protocols self._factory = None @property def factory(self): if self._factory is None: self._factory = self.entry_point.load() return self._factory def load(self, config_uri): config_uri = parse_uri(config_uri) return self.factory(config_uri)