commands: getconfig to use default values, add existence checks

- getconfig and setconfig now both check configvars for existence
- getconfig returns default values when applicable
- setconfig does not side-step type-checks for values

fixes https://github.com/spesmilo/electrum/issues/8607
closes https://github.com/spesmilo/electrum/pull/8608

electrum/commands.py

@@ -59,7 +59,7 @@ from .lnutil import SENT, RECEIVED
 from .lnutil import LnFeatures
 from .lnutil import extract_nodeid
 from .lnpeer import channel_id_from_funding_tx
-from .plugin import run_hook, DeviceMgr
+from .plugin import run_hook, DeviceMgr, Plugins
 from .version import ELECTRUM_VERSION
 from .simple_config import SimpleConfig
 from .invoices import Invoice
@@ -305,7 +305,11 @@ class Commands:
     @command('')
     async def getconfig(self, key):
         """Return a configuration variable. """
-        return self.config.get(key)
+        if Plugins.is_plugin_enabler_config_key(key):
+            return self.config.get(key)
+        else:
+            cv = self.config.cv.from_key(key)
+            return cv.get()
 
     @classmethod
     def _setconfig_normalize_value(cls, key, value):
@@ -326,7 +330,11 @@ class Commands:
             self.daemon.commands_server.rpc_user = value
         if self.daemon and key == SimpleConfig.RPC_PASSWORD.key():
             self.daemon.commands_server.rpc_password = value
-        self.config.set_key(key, value)
+        if Plugins.is_plugin_enabler_config_key(key):
+            self.config.set_key(key, value)
+        else:
+            cv = self.config.cv.from_key(key)
+            cv.set(value)
         return True
 
     @command('')

electrum/plugin.py

@@ -160,6 +160,15 @@ class Plugins(DaemonThread):
         p.close()
         self.logger.info(f"closed {name}")
 
+    @classmethod
+    def is_plugin_enabler_config_key(cls, key: str) -> bool:
+        if not key.startswith('use_'):
+            return False
+        # note: the 'use_' prefix is not sufficient to check, there are
+        #       non-plugin-related config keys that also have it... hence:
+        name = key[4:]
+        return name in cls.find_all_plugins()
+
     def toggle(self, name: str) -> Optional['BasePlugin']:
         p = self.get(name)
         return self.disable(name) if p else self.enable(name)

electrum/simple_config.py

@@ -52,6 +52,9 @@ _logger = get_logger(__name__)
 FINAL_CONFIG_VERSION = 3
 
 
+_config_var_from_key = {}  # type: Dict[str, 'ConfigVar']
+
+
 class ConfigVar(property):
 
     def __init__(
@@ -65,6 +68,7 @@ class ConfigVar(property):
         self._default = default
         self._type = type_
         property.__init__(self, self._get_config_value, self._set_config_value)
+        _config_var_from_key[key] = self
 
     def _get_config_value(self, config: 'SimpleConfig'):
         with config.lock:
@@ -132,6 +136,11 @@ class ConfigVarWithConfig:
     def __repr__(self):
         return f"<ConfigVarWithConfig key={self.key()!r}>"
 
+    def __eq__(self, other) -> bool:
+        if not isinstance(other, ConfigVarWithConfig):
+            return False
+        return self._config is other._config and self._config_var is other._config_var
+
 
 class SimpleConfig(Logger):
     """
@@ -818,10 +827,18 @@ class SimpleConfig(Logger):
         """
         class CVLookupHelper:
             def __getattribute__(self, name: str) -> ConfigVarWithConfig:
+                if name in ("from_key", ):  # don't apply magic, just use standard lookup
+                    return super().__getattribute__(name)
                 config_var = config.__class__.__getattribute__(type(config), name)
                 if not isinstance(config_var, ConfigVar):
                     raise AttributeError()
                 return ConfigVarWithConfig(config=config, config_var=config_var)
+            def from_key(self, key: str) -> ConfigVarWithConfig:
+                try:
+                    config_var = _config_var_from_key[key]
+                except KeyError:
+                    raise KeyError(f"No ConfigVar with key={key!r}") from None
+                return ConfigVarWithConfig(config=config, config_var=config_var)
             def __setattr__(self, name, value):
                 raise Exception(
                     f"Cannot assign value to config.cv.{name} directly. "

electrum/tests/test_simple_config.py

@@ -199,6 +199,12 @@ class Test_SimpleConfig(ElectrumTestCase):
         config.NETWORK_MAX_INCOMING_MSG_SIZE = 2_222_222
         self.assertEqual(5_555_555, config.NETWORK_MAX_INCOMING_MSG_SIZE)
 
+    def test_configvars_from_key(self):
+        config = SimpleConfig(self.options)
+        self.assertEqual(config.cv.NETWORK_SERVER, config.cv.from_key("server"))
+        with self.assertRaises(KeyError):
+            config.cv.from_key("server333")
+
     def test_depth_target_to_fee(self):
         config = SimpleConfig(self.options)
         config.mempool_fees = [[49, 100110], [10, 121301], [6, 153731], [5, 125872], [1, 36488810]]