Isolate the default encoders of subclasses. (#2)

henriquebastos · web-flow · commit 21dd293f4462 · 2025-01-29T15:33:46.000-03:00
* Update poetry and lock. * Replace default encoder lambdas with named functions to facilitate debugging. * Allow JSONEncoder subclasses to have isolated namespaces to compose with their base class without impacting other subclasses. * Revert last 3 commits that were wrongly pushed into main. Revert "Update poetry and lock." This reverts commit 44d33c6. Revert "Replace default encoder lambdas with named functions to facilitate debugging." This reverts commit 83ac429. Revert "Allow JSONEncoder subclasses to have isolated namespaces to compose with their base class without impacting other subclasses." This reverts commit 9e66fac. * Update poetry and lock. (cherry picked from commit 44d33c6) * Replace default encoder lambdas with named functions to facilitate debugging. (cherry picked from commit 83ac429) * Allow JSONEncoder subclasses to have isolated namespaces to compose with their base class without impacting other subclasses. (cherry picked from commit 9e66fac) * Remove debug code. * Revert "Update poetry and lock." This reverts commit 73f6cef. * Fix the order of the typed registry.
diff --git a/jsonstar/default_encoders.py b/jsonstar/default_encoders.py
@@ -18,8 +18,11 @@
 try:
     from pydantic import BaseModel
 
+    def pydantic_dict(o):
+        return o.dict()
+
     PYDANTIC_TYPED_ENCODERS = {
-        BaseModel: lambda o: o.dict(),
+        BaseModel: pydantic_dict,
     }
 except ImportError:
     PYDANTIC_TYPED_ENCODERS = {}
@@ -28,7 +31,10 @@
 try:
     import attrs
 
-    ATTRS_FUNCTIONAL_ENCODERS = [lambda o: attrs.asdict(o)]
+    def attrs_dict(o):
+        return attrs.asdict(o)
+
+    ATTRS_FUNCTIONAL_ENCODERS = [attrs_dict]
 except ImportError:
     ATTRS_FUNCTIONAL_ENCODERS = ()
 
@@ -44,8 +50,12 @@ def encode_timedelta_as_iso_string(duration):
     return f"{sign}P{days}DT{hours:02d}H{minutes:02d}M{seconds:02d}{ms}S"
 
 
+def dataclasses_asdict(o):
+    return dataclasses.asdict(o)
+
+
 DEFAULT_FUNCTIONAL_ENCODERS = [
-    lambda o: dataclasses.asdict(o),
+    dataclasses_asdict,
     *ATTRS_FUNCTIONAL_ENCODERS,
 ]
 
diff --git a/jsonstar/encoder.py b/jsonstar/encoder.py
@@ -20,26 +20,53 @@ def __setitem__(self, type_, function):
                 self.move_to_end(base)
 
 
-class JSONEncoderStar(stdlib_json.JSONEncoder):
+class EncoderMeta(type):
+    def __new__(mcs, name, bases, namespace):
+        if "_default_functional_encoders" not in namespace:
+            namespace["_default_functional_encoders"] = []
+
+        if "_default_typed_encoders" not in namespace:
+            namespace["_default_typed_encoders"] = TypedEncoderRegistry()
+
+        return super().__new__(mcs, name, bases, namespace)
+
+
+class JSONEncoderStar(stdlib_json.JSONEncoder, metaclass=EncoderMeta):
     class FUNCTIONAL:
         """Sentinel type to register a functional encoder."""
 
-    default_typed_encoders = TypedEncoderRegistry(DEFAULT_TYPED_ENCODERS)
-    default_functional_encoders = DEFAULT_FUNCTIONAL_ENCODERS
+    _default_typed_encoders = TypedEncoderRegistry(DEFAULT_TYPED_ENCODERS)
+    _default_functional_encoders = DEFAULT_FUNCTIONAL_ENCODERS
 
     def __init__(self, *args, functional_encoders=(), typed_encoders: dict[type, callable] = NULL_DICT, **kwargs):
         super().__init__(*args, **kwargs)
 
         self._typed_encoders = TypedEncoderRegistry(typed_encoders)
         self._functional_encoders = [*functional_encoders]
 
+    @classmethod
+    def default_functional_encoders(cls):
+        if cls is JSONEncoderStar:
+            return cls._default_functional_encoders
+        else:
+            return cls._default_functional_encoders + cls.__base__.default_functional_encoders()
+
+    @classmethod
+    def default_typed_encoders(cls):
+        if cls is JSONEncoderStar:
+            return cls._default_typed_encoders
+        else:
+            return TypedEncoderRegistry(ChainMap(cls._default_typed_encoders, cls.__base__.default_typed_encoders()))
+
     @property
     def functional_encoders(self):
-        return chain(self._functional_encoders, self.default_functional_encoders)
+        return chain(self._functional_encoders, self.default_functional_encoders())
 
     @property
     def typed_encoders(self):
-        return ChainMap(self._typed_encoders, self.default_typed_encoders)
+        i = self._typed_encoders
+        base = self.default_typed_encoders()
+        return ChainMap(i, base)
 
     def register(self, function, type_=FUNCTIONAL):
         if type_ is self.FUNCTIONAL:
@@ -50,9 +77,9 @@ def register(self, function, type_=FUNCTIONAL):
     @classmethod
     def register_default_encoder(cls, function, type_=FUNCTIONAL):
         if type_ is cls.FUNCTIONAL:
-            cls.default_functional_encoders.append(function)
+            cls._default_functional_encoders.append(function)
         else:
-            cls.default_typed_encoders[type_] = function
+            cls._default_typed_encoders[type_] = function
 
     def default(self, o) -> str:
         for base, encoder in self.typed_encoders.items():
diff --git a/tests/test_encoder.py b/tests/test_encoder.py
@@ -13,29 +13,34 @@ class CustomType:
 
 
 class JSONEncoderTest(JSONEncoderStar):
-    default_typed_encoders = {}
-    default_functional_encoders = []
+    pass
 
 
 @pytest.fixture
 def encoder():
     return JSONEncoderTest()
 
 
+@pytest.fixture(autouse=True)
+def empty_encoder_class(monkeypatch):
+    monkeypatch.setattr(JSONEncoderTest, "_default_functional_encoders", [])
+    monkeypatch.setattr(JSONEncoderTest, "_default_typed_encoders", {})
+
+
 class TestTypedEncoders:
     def test_default_typed_encoders_are_used_when_nothing_else_is_registered(self, encoder):
-        encoder.default_typed_encoders = {CustomType: lambda o: "CustomType default encoder"}
+        encoder.__class__._default_typed_encoders = {CustomType: lambda o: "CustomType default encoder"}
 
         assert encoder.encode(CustomType()) == '"CustomType default encoder"'
 
     def test_typed_encoders_have_precedence_over_default_type_encoders(self, encoder):
-        encoder.default_typed_encoders = {CustomType: lambda o: "CustomType default encoder"}
+        encoder.__class__._default_typed_encoders = {CustomType: lambda o: "CustomType default encoder"}
         encoder.register(lambda o: "CustomType encoder", CustomType)
 
         assert encoder.encode(CustomType()) == '"CustomType encoder"'
 
     def test_typed_encoders_have_precedence_over_functional_encoders(self, encoder):
-        encoder.default_typed_encoders = {CustomType: lambda o: "CustomType default encoder"}
+        encoder.__class__._default_typed_encoders = {CustomType: lambda o: "CustomType default encoder"}
         encoder.register(lambda o: "CustomType encoder", CustomType)
         encoder.register(lambda o: "Functional encoder")
 
@@ -76,12 +81,12 @@ class Child(Mother, Father):
 
 class TestFunctionalEncoders:
     def test_default_functional_encoders_are_used_when_nothing_else_is_registered(self, encoder):
-        encoder.default_functional_encoders = [lambda o: "default functional encoder"]
+        encoder.__class__._default_functional_encoders = [lambda o: "default functional encoder"]
 
         assert encoder.encode(CustomType()) == '"default functional encoder"'
 
     def test_functional_encoders_have_precedence_over_default_functional_encoders(self, encoder):
-        encoder.default_functional_encoders = [lambda o: "default functional encoder"]
+        encoder.__class__._default_functional_encoders = [lambda o: "default functional encoder"]
         encoder.register(lambda o: "functional encoder")
 
         assert encoder.encode(CustomType()) == '"functional encoder"'
diff --git a/tests/test_register_defaults.py b/tests/test_register_defaults.py
@@ -14,8 +14,8 @@ class CustomType:
 class TestDefaultEncoderRegistration:
     @pytest.fixture
     def empty_encoder(self, monkeypatch):
-        monkeypatch.setattr(jsonstar.JSONEncoderStar, "default_functional_encoders", [])
-        monkeypatch.setattr(jsonstar.JSONEncoderStar, "default_typed_encoders", {})
+        monkeypatch.setattr(jsonstar.JSONEncoderStar, "_default_functional_encoders", [])
+        monkeypatch.setattr(jsonstar.JSONEncoderStar, "_default_typed_encoders", {})
 
     def test_register_default_encoder_with_module_api(self, empty_encoder):
         jsonstar.register_default_encoder(lambda o: "functional default encoder")
@@ -30,3 +30,66 @@ def test_register_default_encoder_with_classmethod(self, empty_encoder):
 
         assert jsonstar.dumps(CustomType()) == '"typed default encoder"'
         assert jsonstar.dumps(object()) == '"functional default encoder"'
+
+
+class TestIsolateDefaultsFromEncoderClasses:
+    def test_isolate_functional_defaults_from_different_encoder_classes(self):
+        class EncoderA1(JSONEncoderStar):
+            pass
+
+        class EncoderA2(EncoderA1):
+            pass
+
+        class EncoderB1(JSONEncoderStar):
+            pass
+
+        def a1(o):
+            return o
+
+        def a2(o):
+            return o
+
+        def b1(o):
+            return o
+
+        default_functional_encoders = JSONEncoderStar._default_functional_encoders.copy()
+
+        EncoderA1.register_default_encoder(a1)
+        EncoderA2.register_default_encoder(a2)
+        EncoderB1.register_default_encoder(b1)
+
+        assert JSONEncoderStar.default_functional_encoders() == default_functional_encoders
+        assert EncoderA1.default_functional_encoders() == [a1] + default_functional_encoders
+        assert EncoderA2.default_functional_encoders() == [a2, a1] + default_functional_encoders
+        assert EncoderB1.default_functional_encoders() == [b1] + default_functional_encoders
+
+    def test_isolate_typed_defaults_from_different_encoder_classes(self):
+        class EncoderA1(JSONEncoderStar):
+            pass
+
+        class EncoderA2(EncoderA1):
+            pass
+
+        class EncoderB1(JSONEncoderStar):
+            pass
+
+        def a1(o):
+            return o
+
+        def a2(o):
+            return o
+
+        def b1(o):
+            return o
+
+        default_typed_encoders = JSONEncoderStar._default_typed_encoders.copy()
+
+        EncoderA1.register_default_encoder(a1, str)
+        EncoderA1.register_default_encoder(a1, int)
+        EncoderA2.register_default_encoder(a2, str)
+        EncoderB1.register_default_encoder(b1, str)
+
+        assert JSONEncoderStar.default_typed_encoders() == default_typed_encoders
+        assert EncoderA1.default_typed_encoders() == {**default_typed_encoders, str: a1, int: a1}
+        assert EncoderA2.default_typed_encoders() == {**default_typed_encoders, str: a2, int: a1}
+        assert EncoderB1.default_typed_encoders() == {**default_typed_encoders, str: b1}
