Bug 1255450 - [mach] Implement 'wildcard' settings for enabling sections with user-defined options, r=gps

Some sections should support user-defined options. For example, in an [alias] section, the option names
are not well-defined, rather specified by the user. This patch allows user-defined option names for any
section that has a 'section.*' option defined. Even with 'section.*', option types are still well-defined.

MozReview-Commit-ID: L34W9v9Fy28

--HG--
extra : rebase_source : 9333f552edead9bf1cf464e28ef8fbbb9bed5597

python/mach/docs/settings.rst

@@ -54,6 +54,26 @@ pairs to add to the setting's metadata. The following keys may be specified
 in the ``extra`` dict:
     * ``choices`` - A set of allowed values for the setting.
 
+Wildcards
+---------
+
+Sometimes a section should allow arbitrarily defined options from the user, such
+as the ``alias`` section mentioned above. To define a section like this, use ``*``
+as the option name. For example:
+
+.. parsed-literal::
+
+    ('foo.*', 'string')
+
+This allows configuration files like this:
+
+.. parsed-literal::
+
+    [foo]
+    arbitrary1 = some string
+    arbitrary2 = some other string
+
+
 
 Accessing Settings
 ==================

python/mach/mach/config.py

@@ -213,6 +213,9 @@ class ConfigSettings(collections.Mapping):
             object.__setattr__(self, '_name', name)
             object.__setattr__(self, '_settings', settings)
 
+            wildcard = any(s == '*' for s in self._settings)
+            object.__setattr__(self, '_wildcard', wildcard)
+
         @property
         def options(self):
             try:
@@ -220,11 +223,15 @@ class ConfigSettings(collections.Mapping):
             except NoSectionError:
                 return []
 
-        def _validate(self, option, value):
-            if option not in self._settings:
+        def get_meta(self, option):
+            if option in self._settings:
+                return self._settings[option]
+            if self._wildcard:
+                return self._settings['*']
             raise KeyError('Option not registered with provider: %s' % option)
 
-            meta = self._settings[option]
+        def _validate(self, option, value):
+            meta = self.get_meta(option)
             meta['type_cls'].validate(value)
 
             if 'choices' in meta and value not in meta['choices']:
@@ -242,7 +249,7 @@ class ConfigSettings(collections.Mapping):
             return self._config.has_option(self._name, k)
 
         def __getitem__(self, k):
-            meta = self._settings[k]
+            meta = self.get_meta(k)
 
             if self._config.has_option(self._name, k):
                 v = meta['type_cls'].from_config(self._config, self._name, k)
@@ -255,11 +262,10 @@ class ConfigSettings(collections.Mapping):
             self._validate(k, v)
             return v
 
-
         def __setitem__(self, k, v):
             self._validate(k, v)
+            meta = self.get_meta(k)
 
-            meta = self._settings[k]
             if not self._config.has_section(self._name):
                 self._config.add_section(self._name)
 
@@ -416,7 +422,7 @@ class ConfigSettings(collections.Mapping):
     def option_help(self, section, option):
         """Obtain the translated help messages for an option."""
 
-        meta = self[section]._settings[option]
+        meta = self[section].get_meta(option)
 
         # Providers should always have an en-US translation. If they don't,
         # they are coded wrong and this will raise.

python/mach/mach/test/test_config.py

@@ -88,6 +88,14 @@ class Provider4(object):
     ]
 
 
+@SettingsProvider
+class Provider5(object):
+    config_settings = [
+        ('foo.*', 'string'),
+        ('foo.bar', 'string'),
+    ]
+
+
 class TestConfigSettings(unittest.TestCase):
     def test_empty(self):
         s = ConfigSettings()
@@ -211,6 +219,24 @@ class TestConfigSettings(unittest.TestCase):
         foo.abc = 'b'
         foo.xyz = 'y'
 
+    def test_wildcard_options(self):
+        s = ConfigSettings()
+        s.register_provider(Provider5)
+
+        foo = s.foo
+
+        self.assertIn('*', foo._settings)
+        self.assertNotIn('*', foo)
+
+        foo.baz = 'value1'
+        foo.bar = 'value2'
+
+        self.assertIn('baz', foo)
+        self.assertEqual(foo.baz, 'value1')
+
+        self.assertIn('bar', foo)
+        self.assertEqual(foo.bar, 'value2')
+
     def test_file_reading_single(self):
         temp = NamedTemporaryFile(mode='wt')
         temp.write(CONFIG1)