Remove legacy plugin mechanism in favour of entry points

workflows/__init__.py

@@ -1,25 +1,6 @@
 from __future__ import absolute_import, division, print_function
 
-def load_plugins(paths):
-  '''Import all python files (except test_*) in directories. This is required
-     for registration of services and transport plugins.
-     :param paths: A path or list of paths containing files to import.
-  '''
-  import imp, pkgutil
-  try: # Python3 compatibility
-    basestring = basestring
-  except NameError:
-    basestring = (str, bytes)
-  if isinstance(paths, basestring):
-    paths = list(paths)
-  for _, name, _ in pkgutil.iter_modules(paths):
-    if not name.startswith('test_'):
-      fid, pathname, desc = imp.find_module(name, paths)
-      imp.load_module(name, fid, pathname, desc)
-      if fid:
-        fid.close()
-
-__version__ = '0.62'
+__version__ = '0.63'
 
 def version():
   '''Returns the version number of the installed workflows package.'''
@@ -33,49 +14,3 @@ class DisconnectedError(WorkflowsError):
 
 class AuthenticationError(WorkflowsError):
   '''Indicates the connection could not be established due to incorrect credentials.'''
-
-def add_plugin_register_to_class(*bases):
-  # This function is based off the six library
-  # https://github.com/benjaminp/six
-  #
-  # Copyright (c) 2010-2017 Benjamin Peterson
-  #
-  # Permission is hereby granted, free of charge, to any person obtaining a copy of
-  # this software and associated documentation files (the "Software"), to deal in
-  # the Software without restriction, including without limitation the rights to
-  # use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
-  # the Software, and to permit persons to whom the Software is furnished to do so,
-  # subject to the following conditions:
-  #
-  # The above copyright notice and this permission notice shall be included in all
-  # copies or substantial portions of the Software.
-  #
-  # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-  # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
-  # FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
-  # COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
-  # IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
-  # CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-
-  """Create a base class with a plugin registry metaclass."""
-  # This requires a bit of explanation: the basic idea is to make a dummy
-  # metaclass for one level of class instantiation that replaces itself with
-  # the actual metaclass.
-
-  class PluginRegister(type):
-    '''Define metaclass function to keep a list of all subclasses. This enables
-       looking up subclasses by name.'''
-    def __init__(cls, name, base, attrs):
-      '''Add new subclass to list of all known subclasses.'''
-      if not hasattr(cls, 'plugin_register'):
-        cls.plugin_register = {}
-      else:
-        cls.plugin_register[name] = cls
-
-  class Metametaclass(PluginRegister):
-    '''Dummy metaclass.'''
-    def __new__(cls, name, this_bases, d):
-      '''Return the actual metaclass.'''
-      return PluginRegister(name, bases, d)
-
-  return type.__new__(Metametaclass, 'temporary_class', (), {})

workflows/services/__init__.py

@@ -1,8 +1,6 @@
 from __future__ import absolute_import, division, print_function
 
 import pkg_resources
-import workflows
-from workflows.services.common_service import CommonService
 
 def lookup(service):
   '''Find a service class based on a name.
@@ -26,8 +24,5 @@ def get_known_services():
       e.name: e.load()
       for e in pkg_resources.iter_entry_points('workflows.services')
     })
-  register = CommonService.plugin_register
-  register.update(get_known_services.cache)
+  register = get_known_services.cache.copy()
   return register
-
-workflows.load_plugins(__path__)

workflows/services/common_service.py

@@ -52,7 +52,7 @@ def __init__(self, intval, description):
     self.intval = intval
     self.description = description
 
-class CommonService(workflows.add_plugin_register_to_class(object)):
+class CommonService(object):
   '''
   Base class for workflow services. A service is a piece of software that runs
   in an isolated environment, communicating only via pipes with the outside

workflows/transport/common_transport.py

@@ -4,7 +4,7 @@
 
 import workflows
 
-class CommonTransport():
+class CommonTransport(object):
   '''A common transport class, containing e.g. the logic to connect clients
      to message subscriptions and transactions, so that these can be cleanly
      terminated when the client goes away.'''