PyBitmessage/src/plugins/plugin.py

# -*- coding: utf-8 -*-
"""
Operating with plugins
"""
import logging

import pkg_resources


logger = logging.getLogger('default')


def get_plugins(group, point='', name=None, fallback=None):
    """
    :param str group: plugin group
    :param str point: plugin name prefix
    :param name: exact plugin name
    :param fallback: fallback plugin name

    Iterate through plugins (``connect_plugin`` attribute of entry point)
    which name starts with ``point`` or equals to ``name``.
    If ``fallback`` kwarg specified, plugin with that name yield last.
    """
    for ep in pkg_resources.iter_entry_points('bitmessage.' + group):
        if name and ep.name == name or not point or ep.name.startswith(point):
            try:
                plugin = ep.load().connect_plugin
                if ep.name == fallback:
                    _fallback = plugin
                else:
                    yield plugin
            except (AttributeError,
                    ImportError,
                    ValueError,
                    pkg_resources.DistributionNotFound,
                    pkg_resources.UnknownExtra):
                logger.debug(
                    'Problem while loading %s', ep.name, exc_info=True)
                continue
    try:
        yield _fallback
    except NameError:
        pass


def get_plugin(*args, **kwargs):
    """
    :return: first available plugin from :func:`get_plugins` if any.
    """
    for plugin in get_plugins(*args, **kwargs):
        return plugin