Address review feedback.

CHANGELOG.md

@@ -10,14 +10,14 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Added
 
-- `Suggester` API to compose with `Input` for automatic input suggestions while typing https://github.com/Textualize/textual/issues/2330
-- `SuggestFromList` class to let `Input` widgets get completions from a fixed set of options https://github.com/Textualize/textual/pull/2604
-- `Input` has new component class `input--suggestion` https://github.com/Textualize/textual/pull/2604
+- `Suggester` API to compose with widgets for automatic suggestions https://github.com/Textualize/textual/issues/2330
+- `SuggestFromList` class to let widgets get completions from a fixed set of options https://github.com/Textualize/textual/pull/2604
+- `Input` has a new component class `input--suggestion` https://github.com/Textualize/textual/pull/2604
 
 ### Changed
 
 - Keybinding <kbd>right</kbd> in `Input` is also used to accept a suggestion if the cursor is at the end of the input https://github.com/Textualize/textual/pull/2604
-- `Input.__init__` now accepts a suggester for completion suggestions https://github.com/Textualize/textual/pull/2604
+- `Input.__init__` now accepts a `suggester` attribute for completion suggestions https://github.com/Textualize/textual/pull/2604
 
 
 ## [0.25.0] - 2023-05-17

src/textual/suggester.py

@@ -1,11 +1,12 @@
 from abc import ABC, abstractmethod
 from dataclasses import dataclass
-from typing import TYPE_CHECKING, Iterable, Optional
+from typing import Generic, Iterable, Optional, TypeVar
 
+from ._types import MessageTarget
 from .message import Message
 
-if TYPE_CHECKING:
-    from .widgets import Input
+_SuggestionRequester = TypeVar("_SuggestionRequester", bound=MessageTarget)
+"""Type variable for the message target that will request suggestions."""
 
 
 @dataclass
@@ -18,7 +19,7 @@ class SuggestionReady(Message):
     """The string suggestion."""
 
 
-class Suggester(ABC):
+class Suggester(ABC, Generic[_SuggestionRequester]):
     """Defines how [inputs][textual.widgets.Input] generate completion suggestions.
 
     To define a custom suggester, subclass `Suggester` and implement the async method
@@ -26,22 +27,24 @@ class Suggester(ABC):
     See [`SuggestFromList`][textual.suggester.SuggestFromList] for an example.
     """
 
-    async def get(self, input: "Input", value: str) -> None:
-        """Used by [`Input`][textual.widgets.Input] to get completion suggestions.
+    async def _get_suggestion(
+        self, requester: _SuggestionRequester, value: str
+    ) -> None:
+        """Used by widgets to get completion suggestions.
 
         Note:
             When implementing custom suggesters, this method does not need to be
             overridden.
 
         Args:
-            input: The input widget that requested a suggestion.
+            requester: The message target that requested a suggestion.
             value: The current input value to complete.
         """
         suggestion = await self.get_suggestion(value)
         if suggestion is None:
             return
 
-        input.post_message(SuggestionReady(value, suggestion))
+        requester.post_message(SuggestionReady(value, suggestion))
 
     @abstractmethod
     async def get_suggestion(self, value: str) -> Optional[str]:
@@ -55,10 +58,10 @@ class Suggester(ABC):
         Returns:
             A valid suggestion or `None`.
         """
-        raise NotImplementedError()
+        pass
 
 
-class SuggestFromList(Suggester):
+class SuggestFromList(Suggester[_SuggestionRequester]):
     """Give completion suggestions based on a fixed list of options."""
 
     def __init__(self, suggestions: Iterable[str]) -> None:
@@ -73,10 +76,10 @@ class SuggestFromList(Suggester):
         """Gets a completion from the given possibilities.
 
         Args:
-            value: The current value of the input widget.
+            value: The current value.
 
         Returns:
-            A valid suggestion or `None`.
+            A valid completion suggestion or `None`.
         """
         for suggestion in self.suggestions:
             if suggestion.startswith(value):

src/textual/widgets/_input.py

@@ -156,7 +156,7 @@ class Input(Widget, can_focus=True):
     _cursor_visible = reactive(True)
     password = reactive(False)
     max_size: reactive[int | None] = reactive(None)
-    suggester: Suggester | None
+    suggester: Suggester[Input] | None
     """The suggester used to provide completions as the user types."""
     _suggestion = reactive("")
     """A completion suggestion for the current value in the input."""
@@ -284,7 +284,7 @@ class Input(Widget, can_focus=True):
     async def watch_value(self, value: str) -> None:
         self._suggestion = ""
         if self.suggester and value:
-            self.call_next(self.suggester.get, self, value)
+            self.call_next(self.suggester._get_suggestion, self, value)
         if self.styles.auto_dimensions:
             self.refresh(layout=True)
         self.post_message(self.Changed(self, value))