Remove TODO now that attrs is released (#1453)

griptape/tasks/prompt_task.py

@@ -1,9 +1,9 @@
 from __future__ import annotations
 
 import logging
-from typing import TYPE_CHECKING, Callable, Literal, Optional, Union
+from typing import TYPE_CHECKING, Callable, Optional, Union
 
-from attrs import NOTHING, Factory, define, field
+from attrs import NOTHING, Factory, NothingType, define, field
 
 from griptape.artifacts import BaseArtifact, ListArtifact, TextArtifact
 from griptape.common import PromptStack
@@ -31,7 +31,7 @@ class PromptTask(RuleMixin, BaseTask):
         default=Factory(lambda self: self.default_generate_system_template, takes_self=True),
         kw_only=True,
     )
-    conversation_memory: Union[Optional[BaseConversationMemory], Literal[NOTHING]] = field(  # pyright: ignore[reportInvalidTypeForm] TODO: Replace with [NothingType](https://github.com/python-attrs/attrs/pull/1358)
+    conversation_memory: Union[Optional[BaseConversationMemory], NothingType] = field(
         default=Factory(lambda: NOTHING), kw_only=True
     )
     _input: Union[str, list, tuple, BaseArtifact, Callable[[BaseTask], BaseArtifact]] = field(
@@ -79,7 +79,7 @@ def prompt_stack(self) -> PromptStack:
         if self.output:
             stack.add_assistant_message(self.output)
 
-        if memory is not None:
+        if memory is not None and memory is not NOTHING:
             # insert memory into the stack right before the user messages
             memory.add_to_prompt_stack(self.prompt_driver, stack, 1 if system_template else 0)
 
@@ -105,15 +105,17 @@ def after_run(self) -> None:
             self.output.to_text() if self.output is not None else "",
         )
         structure = self.structure
+        conversation_memory = self.conversation_memory
         if (
             structure is not None
             and structure.conversation_memory_strategy == "per_task"
-            and self.conversation_memory is not None
+            and conversation_memory is not None
+            and conversation_memory is not NOTHING
             and self.output is not None
         ):
             run = Run(input=self.input, output=self.output)
 
-            self.conversation_memory.add_run(run)
+            conversation_memory.add_run(run)
 
     def try_run(self) -> BaseArtifact:
         message = self.prompt_driver.run(self.prompt_stack)