options: defaults are a class attribute

mitmproxy/optmanager.py

@@ -54,15 +54,6 @@ class OptManager(metaclass=_DefaultsMeta):
         # ._initialized = True as the final operation.
         instance = super().__new__(cls)
         instance.__dict__["_opts"] = {}
-
-        defaults = {}
-        for klass in reversed(inspect.getmro(cls)):
-            for p in inspect.signature(klass.__init__).parameters.values():
-                if p.kind in (p.KEYWORD_ONLY, p.POSITIONAL_OR_KEYWORD):
-                    if not p.default == p.empty:
-                        defaults[p.name] = p.default
-        instance.__dict__["_defaults"] = defaults
-
         return instance
 
     def __init__(self):
@@ -143,6 +134,10 @@ class OptManager(metaclass=_DefaultsMeta):
         """
         self.update(**self._defaults)
 
+    @classmethod
+    def default(klass, opt):
+        return copy.deepcopy(klass._defaults[opt])
+
     def update(self, **kwargs):
         updated = set(kwargs.keys())
         for k, v in kwargs.items():

test/mitmproxy/test_optmanager.py

@@ -30,6 +30,11 @@ class TD2(TD):
 
 
 def test_defaults():
+    assert TD2.default("one") == "done"
+    assert TD2.default("two") == "dtwo"
+    assert TD2.default("three") == "dthree"
+    assert TD2.default("four") == "dfour"
+
     o = TD2()
     assert o._defaults == {
         "one": "done",