From 7794bcb680300249cd9be48562ce190eed8b9cff Mon Sep 17 00:00:00 2001
From: Robert Craigie <robert@craigie.dev>
Date: Wed, 22 May 2024 14:40:03 +0100
Subject: [PATCH] chore(messages): add back-compat for isinstance() checks

---
 src/anthropic/_streaming.py          | 48 ++++++++++++++++++++++++++--
 tests/lib/streaming/test_messages.py |  8 ++++-
 tests/test_streaming.py              |  8 +++++
 3 files changed, 61 insertions(+), 3 deletions(-)

diff --git a/src/anthropic/_streaming.py b/src/anthropic/_streaming.py
index 73474c33..d43e2e6a 100644
--- a/src/anthropic/_streaming.py
+++ b/src/anthropic/_streaming.py
@@ -1,8 +1,10 @@
 # Note: initially copied from /~https://github.com/florimondmanca/httpx-sse/blob/master/src/httpx_sse/_decoders.py
 from __future__ import annotations
 
+import abc
 import json
 import inspect
+import warnings
 from types import TracebackType
 from typing import TYPE_CHECKING, Any, Generic, TypeVar, Iterator, AsyncIterator, cast
 from typing_extensions import Self, Protocol, TypeGuard, override, get_origin, runtime_checkable
@@ -18,7 +20,28 @@
 _T = TypeVar("_T")
 
 
-class Stream(Generic[_T]):
+class _SyncStreamMeta(abc.ABCMeta):
+    @override
+    def __instancecheck__(self, instance: Any) -> bool:
+        # we override the `isinstance()` check for `Stream`
+        # as a previous version of the `MessageStream` class
+        # inherited from `Stream` & without this workaround,
+        # changing it to not inherit would be a breaking change.
+
+        from .lib.streaming import MessageStream
+
+        if isinstance(instance, MessageStream):
+            warnings.warn(
+                "Using `isinstance()` to check if a `MessageStream` object is an instance of `Stream` is deprecated & will be removed in the next major version",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+            return True
+
+        return False
+
+
+class Stream(Generic[_T], metaclass=_SyncStreamMeta):
     """Provides the core interface to iterate over a synchronous stream response."""
 
     response: httpx.Response
@@ -114,7 +137,28 @@ def close(self) -> None:
         self.response.close()
 
 
-class AsyncStream(Generic[_T]):
+class _AsyncStreamMeta(abc.ABCMeta):
+    @override
+    def __instancecheck__(self, instance: Any) -> bool:
+        # we override the `isinstance()` check for `AsyncStream`
+        # as a previous version of the `AsyncMessageStream` class
+        # inherited from `AsyncStream` & without this workaround,
+        # changing it to not inherit would be a breaking change.
+
+        from .lib.streaming import AsyncMessageStream
+
+        if isinstance(instance, AsyncMessageStream):
+            warnings.warn(
+                "Using `isinstance()` to check if a `AsyncMessageStream` object is an instance of `AsyncStream` is deprecated & will be removed in the next major version",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+            return True
+
+        return False
+
+
+class AsyncStream(Generic[_T], metaclass=_AsyncStreamMeta):
     """Provides the core interface to iterate over an asynchronous stream response."""
 
     response: httpx.Response
diff --git a/tests/lib/streaming/test_messages.py b/tests/lib/streaming/test_messages.py
index 4d247238..5c872af5 100644
--- a/tests/lib/streaming/test_messages.py
+++ b/tests/lib/streaming/test_messages.py
@@ -8,7 +8,7 @@
 import pytest
 from respx import MockRouter
 
-from anthropic import Anthropic, AsyncAnthropic
+from anthropic import Stream, Anthropic, AsyncStream, AsyncAnthropic
 from anthropic.lib.streaming import MessageStream, AsyncMessageStream
 from anthropic.types.message import Message
 from anthropic.types.message_stream_event import MessageStreamEvent
@@ -124,6 +124,9 @@ def test_basic_response(self, respx_mock: MockRouter) -> None:
             model="claude-3-opus-20240229",
             event_handler=SyncEventTracker,
         ) as stream:
+            with pytest.warns(DeprecationWarning):
+                assert isinstance(stream, Stream)
+
             assert_basic_response(stream, stream.get_final_message())
 
     @pytest.mark.respx(base_url=base_url)
@@ -163,6 +166,9 @@ async def test_basic_response(self, respx_mock: MockRouter) -> None:
             model="claude-3-opus-20240229",
             event_handler=AsyncEventTracker,
         ) as stream:
+            with pytest.warns(DeprecationWarning):
+                assert isinstance(stream, AsyncStream)
+
             assert_basic_response(stream, await stream.get_final_message())
 
     @pytest.mark.asyncio
diff --git a/tests/test_streaming.py b/tests/test_streaming.py
index f9ad7182..9e8908ae 100644
--- a/tests/test_streaming.py
+++ b/tests/test_streaming.py
@@ -216,6 +216,14 @@ def body() -> Iterator[bytes]:
     assert sse.json() == {"content": "известни"}
 
 
+def test_isinstance_check(client: Anthropic, async_client: AsyncAnthropic) -> None:
+    async_stream = AsyncStream(cast_to=object, client=async_client, response=httpx.Response(200, content=b"foo"))
+    assert isinstance(async_stream, AsyncStream)
+
+    sync_stream = Stream(cast_to=object, client=client, response=httpx.Response(200, content=b"foo"))
+    assert isinstance(sync_stream, Stream)
+
+
 async def to_aiter(iter: Iterator[bytes]) -> AsyncIterator[bytes]:
     for chunk in iter:
         yield chunk