make channel_priority an enum with options

conda/base/constants.py

@@ -10,10 +10,10 @@
 """
 from __future__ import absolute_import, division, print_function, unicode_literals
 
-from enum import Enum
+from enum import Enum, EnumMeta
 from os.path import join
 
-from ..common.compat import itervalues, on_win
+from ..common.compat import itervalues, on_win, six_with_metaclass, string_types
 
 PREFIX_PLACEHOLDER = ('/opt/anaconda1anaconda2'
                       # this is intentionally split into parts, such that running
@@ -169,6 +169,34 @@ def __str__(self):
         return self.value
 
 
+class ChannelPriorityMeta(EnumMeta):
+
+    def __call__(cls, value, *args, **kwargs):
+        try:
+            return super(ChannelPriorityMeta, cls).__call__(value, *args, **kwargs)
+        except ValueError:
+            if isinstance(value, string_types):
+                from .._vendor.auxlib.type_coercion import typify
+                value = typify(value)
+            if value is True:
+                value = 'flexible'
+            elif value is False:
+                value = cls.DISABLED
+            return super(ChannelPriorityMeta, cls).__call__(value, *args, **kwargs)
+
+
+class ChannelPriority(six_with_metaclass(ChannelPriorityMeta, Enum)):
+    __name__ = "ChannelPriority"
+
+    STRICT = 'strict'
+    STRICT_OR_FLEXIBLE = 'strict_or_flexible'
+    FLEXIBLE = 'flexible'
+    DISABLED = 'disabled'
+
+    def __str__(self):
+        return self.value
+
+
 # Magic files for permissions determination
 PACKAGE_CACHE_MAGIC_FILE = 'urls.txt'
 PREFIX_MAGIC_FILE = join('conda-meta', 'history')

conda/base/context.py

@@ -10,10 +10,11 @@
 import platform
 import sys
 
-from .constants import (APP_NAME, DEFAULTS_CHANNEL_NAME, DEFAULT_AGGRESSIVE_UPDATE_PACKAGES,
-                        DEFAULT_CHANNELS, DEFAULT_CHANNEL_ALIAS, DEFAULT_CUSTOM_CHANNELS,
-                        DepsModifier, ERROR_UPLOAD_URL, PLATFORM_DIRECTORIES, PREFIX_MAGIC_FILE,
-                        PathConflict, ROOT_ENV_NAME, SEARCH_PATH, SafetyChecks, UpdateModifier)
+from .constants import (APP_NAME, ChannelPriority, DEFAULTS_CHANNEL_NAME,
+                        DEFAULT_AGGRESSIVE_UPDATE_PACKAGES, DEFAULT_CHANNELS,
+                        DEFAULT_CHANNEL_ALIAS, DEFAULT_CUSTOM_CHANNELS, DepsModifier,
+                        ERROR_UPLOAD_URL, PLATFORM_DIRECTORIES, PREFIX_MAGIC_FILE, PathConflict,
+                        ROOT_ENV_NAME, SEARCH_PATH, SafetyChecks, UpdateModifier)
 from .. import __version__ as CONDA_VERSION
 from .._vendor.appdirs import user_data_dir
 from .._vendor.auxlib.decorators import memoize, memoizedproperty
@@ -169,7 +170,7 @@ class Context(Configuration):
     _channel_alias = PrimitiveParameter(DEFAULT_CHANNEL_ALIAS,
                                         aliases=('channel_alias',),
                                         validation=channel_alias_validation)
-    channel_priority = PrimitiveParameter(True)
+    channel_priority = PrimitiveParameter(ChannelPriority.FLEXIBLE)
     _channels = SequenceParameter(string_types, default=(DEFAULTS_CHANNEL_NAME,),
                                   aliases=('channels', 'channel',))  # channel for args.channel
     _custom_channels = MapParameter(string_types, DEFAULT_CUSTOM_CHANNELS,

conda/cli/main_config.py

@@ -13,7 +13,8 @@
 from .. import CondaError
 from .._vendor.auxlib.entity import EntityEncoder
 from .._vendor.toolz import concat, groupby
-from ..base.constants import DepsModifier, PathConflict, SafetyChecks, UpdateModifier
+from ..base.constants import (ChannelPriority, DepsModifier, PathConflict, SafetyChecks,
+                              UpdateModifier)
 from ..base.context import context, sys_rc_path, user_rc_path
 from ..common.compat import Mapping, Sequence, isiterable, iteritems, itervalues, string_types
 from ..common.configuration import pretty_list, pretty_map
@@ -346,6 +347,7 @@ def enum_representer(dumper, data):
         yaml.representer.RoundTripRepresenter.add_representer(PathConflict, enum_representer)
         yaml.representer.RoundTripRepresenter.add_representer(DepsModifier, enum_representer)
         yaml.representer.RoundTripRepresenter.add_representer(UpdateModifier, enum_representer)
+        yaml.representer.RoundTripRepresenter.add_representer(ChannelPriority, enum_representer)
 
         try:
             with open(rc_path, 'w') as rc:

conda/common/compat.py

@@ -149,6 +149,21 @@ def _clone_with_metaclass(Class):
     return _clone_with_metaclass
 
 
+def six_with_metaclass(meta, *bases):
+    """Create a base class with a 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 metaclass(type):
+
+        def __new__(cls, name, this_bases, d):
+            return meta(name, bases, d)
+
+        @classmethod
+        def __prepare__(cls, name, this_bases):
+            return meta.__prepare__(name, bases)
+    return type.__new__(metaclass, str('temporary_class'), (), {})
+
 
 NoneType = type(None)
 primitive_types = tuple(chain(string_types, integer_types, (float, complex, bool, NoneType)))

tests/base/test_constants.py

@@ -1,6 +1,7 @@
 # -*- coding: utf-8 -*-
 from __future__ import absolute_import, division, print_function, unicode_literals
 
+from conda.base.constants import ChannelPriority
 from conda.common.constants import NULL
 from logging import getLogger
 
@@ -9,3 +10,10 @@
 
 def test_null_is_falsey():
     assert not NULL
+
+
+def test_ChannelPriority():
+    assert ChannelPriority("strict") == ChannelPriority.STRICT
+    assert ChannelPriority["STRICT"] == ChannelPriority.STRICT
+    assert ChannelPriority(False) == ChannelPriority.DISABLED
+    assert ChannelPriority('false') == ChannelPriority.DISABLED

tests/base/test_context.py

@@ -12,7 +12,7 @@
 from conda._vendor.auxlib.collection import AttrDict
 from conda._vendor.auxlib.ish import dals
 from conda._vendor.toolz.itertoolz import concat
-from conda.base.constants import PathConflict
+from conda.base.constants import PathConflict, ChannelPriority
 from conda.base.context import context, reset_context
 from conda.common.compat import odict, iteritems
 from conda.common.configuration import ValidationError, YamlRawParameter
@@ -61,6 +61,7 @@ def setUp(self):
           ftps: false
           rsync: 'false'
         aggressive_update_packages: []
+        channel_priority: false
         """)
         reset_context()
         rd = odict(testdata=YamlRawParameter.make_raw_parameters('testdata', yaml_load(string)))
@@ -255,6 +256,9 @@ def test_aggressive_update_packages(self):
         with env_var('CONDA_AGGRESSIVE_UPDATE_PACKAGES', ','.join(specs), reset_context):
             assert context.aggressive_update_packages == tuple(MatchSpec(s) for s in specs)
 
+    def test_channel_priority(self):
+        assert context.channel_priority == ChannelPriority.DISABLED
+
 
 class ContextDefaultRcTests(TestCase):