Allow overwrite max_iter in ReAct (#8096)

* allow overriding max_iter in ReAct

* add test for retrying

Author: TomeHirata

dspy/predict/react.py

@@ -73,7 +73,8 @@ def _format_trajectory(self, trajectory: dict[str, Any]):
 
     def forward(self, **input_args):
         trajectory = {}
-        for idx in range(self.max_iters):
+        max_iters = input_args.pop("max_iters", self.max_iters)
+        for idx in range(max_iters):
             pred = self._call_with_potential_trajectory_truncation(self.react, trajectory, **input_args)
 
             trajectory[f"thought_{idx}"] = pred.next_thought
@@ -173,8 +174,4 @@ def truncate_trajectory(self, trajectory):
 TOPIC 06: Idiomatically allowing tools that maintain state across iterations, but not across different `forward` calls.
     * So the tool would be newly initialized at the start of each `forward` call, but maintain state across iterations.
     * This is pretty useful for allowing the agent to keep notes or count certain things, etc.
-
-TOPIC 07: Make max_iters a bit more expressive.
-    * Allow passing `max_iters` in forward to overwrite the default.
-    * Get rid of `last_iteration: bool` in the format function. It's not necessary now.
 """

tests/predict/test_react.py

@@ -1,10 +1,7 @@
-from dataclasses import dataclass
-
 from pydantic import BaseModel
 
 import dspy
-from dspy.predict import react
-from dspy.utils.dummies import DummyLM, dummy_rm
+from dspy.utils.dummies import DummyLM
 import litellm
 
 # def test_example_no_tools():
@@ -276,3 +273,38 @@ def mock_react(**kwargs):
     assert "thought_0" not in result.trajectory
     assert "thought_2" in result.trajectory
     assert result.output_text == "Final output"
+
+
+def test_error_retry():
+    def foo(a, b):
+        raise Exception("tool error")
+
+    react = dspy.ReAct("a, b -> c:int", tools=[foo])
+    max_iters = 2
+    lm = DummyLM(
+        [
+            {"next_thought": "I need to add two numbers.", "next_tool_name": "foo", "next_tool_args": {"a": 1, "b": 2}},
+            {"next_thought": "I need to add two numbers.", "next_tool_name": "foo", "next_tool_args": {"a": 1, "b": 2}},
+            {"reasoning": "I added the numbers successfully", "c": 3},
+        ]
+    )
+    dspy.settings.configure(lm=lm)
+
+    outputs = react(a=1, b=2, max_iters=max_iters)
+    expected_trajectory = {
+        "thought_0": "I need to add two numbers.",
+        "tool_name_0": "foo",
+        "tool_args_0": {
+            "a": 1,
+            "b": 2,
+        },
+        'observation_0': 'Failed to execute: tool error',
+        'thought_1': 'I need to add two numbers.',
+        'tool_name_1': 'foo',
+        "tool_args_1": {
+            "a": 1,
+            "b": 2,
+        },
+        'observation_1': 'Failed to execute: tool error',
+    }
+    assert outputs.trajectory == expected_trajectory