feat: add WuttaConfigProfile base class

convenience for use with various configurable features/services etc.

src/wuttjamaican/conf.py

@@ -1013,3 +1013,89 @@ def make_config(
             extension.startup(config)
 
     return config
+
+
+class WuttaConfigProfile:
+    """
+    Base class to represent a configured "profile" in the context of
+    some service etc.
+
+    :param config: App :term:`config object`.
+
+    :param key: Config key for the profile.
+
+    Generally each subclass will represent a certain type of config
+    profile, and each instance will represent a single profile
+    (identified by the ``key``).
+    """
+
+    def __init__(self, config, key):
+        self.config = config
+        self.app = self.config.get_app()
+        self.key = key
+        self.load()
+
+    @property
+    def section(self):
+        """
+        The primary config section under which profiles may be
+        defined.
+
+        There is no default; each subclass must declare it.
+
+        This corresponds to the typical INI file section, for instance
+        a section of ``wutta.telemetry`` assumes file contents like:
+
+        .. code-block:: ini
+
+           [wutta.telemetry]
+           default.submit_url = /nodes/telemetry
+           special.submit_url = /nodes/telemetry-special
+        """
+        raise NotImplementedError
+
+    def load(self):
+        """
+        Read all relevant settings from config, and assign attributes
+        on the profile instance accordingly.
+
+        There is no default logic but subclass will generally override.
+
+        While a caller can use :meth:`get_str()` to obtain arbitrary
+        config values dynamically, it is often useful for the profile
+        to pre-load some config values.  This allows "smarter"
+        interpretation of config values in some cases, and at least
+        ensures common/shared logic.
+
+        There is no constraint or other guidance in terms of which
+        profile attributes might be set by this method.  Subclass
+        should document if necessary.
+        """
+
+    def get_str(self, option, **kwargs):
+        """
+        Get a string value for the profile, from config.
+
+        :param option: Name of config option for which to return value.
+
+        This just calls :meth:`~WuttaConfig.get()` on the config
+        object, but for a particular setting name which it composes
+        dynamically.
+
+        Assuming a config file like:
+
+        .. code-block:: ini
+
+           [wutta.telemetry]
+           default.submit_url = /nodes/telemetry
+
+        Then a ``default`` profile under the ``wutta.telemetry``
+        section would effectively have a ``submit_url`` option::
+
+           class TelemetryProfile(WuttaConfigProfile):
+               section = "wutta.telemetry"
+
+           profile = TelemetryProfile("default")
+           url = profile.get_str("submit_url")
+        """
+        return self.config.get(f'{self.section}.{self.key}.{option}', **kwargs)

tests/test_conf.py

@@ -12,7 +12,7 @@ from wuttjamaican import conf as mod
 from wuttjamaican import conf
 from wuttjamaican.exc import ConfigurationError
 from wuttjamaican.app import AppHandler
-from wuttjamaican.testing import FileTestCase
+from wuttjamaican.testing import FileTestCase, ConfigTestCase
 
 
 class TestWuttaConfig(FileTestCase):
@@ -867,3 +867,21 @@ class TestMakeConfig(FileTestCase):
                 foo_cls.assert_called_once_with()
                 foo_obj.configure.assert_called_once_with(testconfig)
                 foo_obj.startup.assert_called_once_with(testconfig)
+
+
+class TestWuttaConfigProfile(ConfigTestCase):
+
+    def make_profile(self, key):
+        return mod.WuttaConfigProfile(self.config, key)
+
+    def test_section(self):
+        profile = self.make_profile('default')
+        self.assertRaises(NotImplementedError, getattr, profile, 'section')
+
+    def test_get_str(self):
+        self.config.setdefault('wutta.telemetry.default.submit_url', '/nodes/telemetry')
+        with patch.object(mod.WuttaConfigProfile, 'section', new='wutta.telemetry'):
+            profile = self.make_profile('default')
+            self.assertEqual(profile.section, 'wutta.telemetry')
+            url = profile.get_str('submit_url')
+            self.assertEqual(url, '/nodes/telemetry')