Revert "Use structural typing for the interface"

This reverts commit b8ab990.

Author: dandavison

temporalio/client.py

@@ -66,6 +66,7 @@
 from temporalio.converter import (
     DataConverter,
     SerializationContext,
+    WithSerializationContext,
     WorkflowSerializationContext,
 )
 from temporalio.service import (
@@ -2736,7 +2737,7 @@ class AsyncActivityIDReference:
     activity_id: str
 
 
-class AsyncActivityHandle:
+class AsyncActivityHandle(WithSerializationContext):
     """Handle representing an external activity for completion and heartbeat."""
 
     def __init__(

temporalio/converter.py

@@ -28,15 +28,13 @@
     Mapping,
     NewType,
     Optional,
-    Protocol,
     Sequence,
     Tuple,
     Type,
     TypeVar,
     Union,
     get_type_hints,
     overload,
-    runtime_checkable,
 )
 
 import google.protobuf.duration_pb2
@@ -139,13 +137,10 @@ class ActivitySerializationContext(BaseWorkflowSerializationContext):
     is_local: bool
 
 
-@runtime_checkable
-class WithSerializationContext(Protocol):
+# TODO: duck typing or nominal typing?
+class WithSerializationContext(ABC):
     """Interface for classes that can use serialization context.
 
-    To use serialization context in your class, implementing this interface is sufficient; you do
-    not need to inherit from this class.
-
     The following classes may implement this interface:
     - :py:class:`PayloadConverter`
     - :py:class:`PayloadCodec`
@@ -337,7 +332,7 @@ def from_payload(
         raise NotImplementedError
 
 
-class CompositePayloadConverter(PayloadConverter):
+class CompositePayloadConverter(PayloadConverter, WithSerializationContext):
     """Composite payload converter that delegates to a list of encoding payload converters.
 
     Encoding/decoding are attempted on each payload converter successively until

tests/test_serialization_context.py

@@ -38,6 +38,7 @@
     PayloadCodec,
     PayloadConverter,
     SerializationContext,
+    WithSerializationContext,
     WorkflowSerializationContext,
 )
 from temporalio.exceptions import ApplicationError
@@ -65,7 +66,9 @@ class TraceData:
     items: list[TraceItem] = field(default_factory=list)
 
 
-class SerializationContextPayloadConverter(EncodingPayloadConverter):
+class SerializationContextPayloadConverter(
+    EncodingPayloadConverter, WithSerializationContext
+):
     def __init__(self):
         self.context: Optional[SerializationContext] = None
 
@@ -130,7 +133,9 @@ def from_payload(
         return value
 
 
-class SerializationContextCompositePayloadConverter(CompositePayloadConverter):
+class SerializationContextCompositePayloadConverter(
+    CompositePayloadConverter, WithSerializationContext
+):
     def __init__(self):
         super().__init__(
             SerializationContextPayloadConverter(),
@@ -995,7 +1000,7 @@ async def run(self) -> Never:
 test_traces: dict[str, list[TraceItem]] = defaultdict(list)
 
 
-class FailureConverterWithContext(DefaultFailureConverter):
+class FailureConverterWithContext(DefaultFailureConverter, WithSerializationContext):
     def __init__(self):
         super().__init__(encode_common_attributes=False)
         self.context: Optional[SerializationContext] = None
@@ -1126,7 +1131,7 @@ async def test_failure_converter_with_context(client: Client):
 # Test payload codec
 
 
-class PayloadCodecWithContext(PayloadCodec):
+class PayloadCodecWithContext(PayloadCodec, WithSerializationContext):
     def __init__(self):
         self.context: Optional[SerializationContext] = None
         self.encode_called_with_context = False
@@ -1427,7 +1432,7 @@ async def test_child_workflow_codec_with_context(client: Client):
 # Payload codec: test decode context matches encode context
 
 
-class PayloadEncryptionCodec(PayloadCodec):
+class PayloadEncryptionCodec(PayloadCodec, WithSerializationContext):
     """
     The outbound data for encoding must always be the string "outbound". "Encrypt" it by replacing
     it with a key that is derived from the context available during encoding. On decryption, assert
@@ -1592,7 +1597,7 @@ async def test_decode_context_matches_encode_context(
 # Test nexus payload codec
 
 
-class AssertNexusLacksContextPayloadCodec(PayloadCodec):
+class AssertNexusLacksContextPayloadCodec(PayloadCodec, WithSerializationContext):
     def __init__(self):
         self.context = None
 
@@ -1674,7 +1679,9 @@ class PydanticData(BaseModel):
     trace: List[str] = []
 
 
-class PydanticJSONConverterWithContext(PydanticJSONPlainPayloadConverter):
+class PydanticJSONConverterWithContext(
+    PydanticJSONPlainPayloadConverter, WithSerializationContext
+):
     def __init__(self):
         super().__init__()
         self.context: Optional[SerializationContext] = None
@@ -1693,7 +1700,7 @@ def to_payload(self, value: Any) -> Optional[temporalio.api.common.v1.Payload]:
         return super().to_payload(value)
 
 
-class PydanticConverterWithContext(CompositePayloadConverter):
+class PydanticConverterWithContext(CompositePayloadConverter, WithSerializationContext):
     def __init__(self):
         super().__init__(
             *(
@@ -1751,7 +1758,9 @@ class UserMethodCalledError(Exception):
     pass
 
 
-class CustomEncodingPayloadConverter(JSONPlainPayloadConverter):
+class CustomEncodingPayloadConverter(
+    JSONPlainPayloadConverter, WithSerializationContext
+):
     @property
     def encoding(self) -> str:
         return "custom-encoding-that-does-not-clash-with-default-converters"