Use stevedore to load formatter plugins

2 files changed, 17 insertions, 18 deletions

diff --git a/cliff/display.py b/cliff/display.py
index 44da7e1..edea1f3 100644
--- a/cliff/display.py
+++ b/cliff/display.py
@@ -3,7 +3,7 @@
 import abc
 import logging
 
-import pkg_resources
+import stevedore
 
 from .command import Command
 
@@ -18,7 +18,7 @@ class DisplayCommandBase(Command):
 
     def __init__(self, app, app_args):
         super(DisplayCommandBase, self).__init__(app, app_args)
-        self.load_formatter_plugins()
+        self.formatters = self._load_formatter_plugins()
 
     @abc.abstractproperty
     def formatter_namespace(self):
@@ -28,16 +28,12 @@ class DisplayCommandBase(Command):
     def formatter_default(self):
         "String specifying the name of the default formatter."
 
-    def load_formatter_plugins(self):
-        self.formatters = {}
-        for ep in pkg_resources.iter_entry_points(self.formatter_namespace):
-            try:
-                self.formatters[ep.name] = ep.load()()
-            except Exception as err:
-                LOG.error(err)
-                if self.app_args.debug:
-                    raise
-        return
+    def _load_formatter_plugins(self):
+        # Here so tests can override
+        return stevedore.ExtensionManager(
+            self.formatter_namespace,
+            invoke_on_load=True,
+        )
 
     def get_parser(self, prog_name):
         parser = super(DisplayCommandBase, self).get_parser(prog_name)
@@ -45,7 +41,7 @@ class DisplayCommandBase(Command):
             title='output formatters',
             description='output formatter options',
         )
-        formatter_choices = sorted(self.formatters.keys())
+        formatter_choices = sorted(self.formatters.names())
         formatter_default = self.formatter_default
         if formatter_default not in formatter_choices:
             formatter_default = formatter_choices[0]
@@ -65,8 +61,8 @@ class DisplayCommandBase(Command):
             metavar='COLUMN',
             help='specify the column(s) to include, can be repeated',
         )
-        for name, formatter in sorted(self.formatters.items()):
-            formatter.add_argument_group(parser)
+        for formatter in self.formatters:
+            formatter.obj.add_argument_group(parser)
         return parser
 
     @abc.abstractmethod
@@ -80,7 +76,7 @@ class DisplayCommandBase(Command):
         """
 
     def run(self, parsed_args):
-        self.formatter = self.formatters[parsed_args.formatter]
+        self.formatter = self.formatters[parsed_args.formatter].obj
         column_names, data = self.take_action(parsed_args)
         self.produce_output(parsed_args, column_names, data)
         return 0
diff --git a/cliff/tests/test_lister.py b/cliff/tests/test_lister.py
index c0452d5..7d1876f 100644
--- a/cliff/tests/test_lister.py
+++ b/cliff/tests/test_lister.py
@@ -1,5 +1,7 @@
 #!/usr/bin/env python
 
+import weakref
+
 from cliff.lister import Lister
 
 import mock
@@ -9,6 +11,7 @@ class FauxFormatter(object):
 
     def __init__(self):
         self.args = []
+        self.obj = weakref.proxy(self)
 
     def emit_list(self, columns, data, stdout, args):
         self.args.append((columns, data))
@@ -16,8 +19,8 @@ class FauxFormatter(object):
 
 class ExerciseLister(Lister):
 
-    def load_formatter_plugins(self):
-        self.formatters = {
+    def _load_formatter_plugins(self):
+        return {
             'test': FauxFormatter(),
         }
         return