Add blocking param to click.prompt

Author: smurfix

CHANGES.rst

@@ -5,6 +5,11 @@ Version 8.3.0
 
 Released 2025-09-15
 
+-   **Important: Breaking asyncclick change**: :func:`asyncclick.prompt` is now
+    async. It accepts a new `blocking` parameter to switch between keeping the
+    async loop running (`False`) and not going belly-up when the user interrupts
+    it using Control-C (`True`). `True` thus is the default (for now).
+
 -   **Improved flag option handling**: Reworked the relationship between ``flag_value``
     and ``default`` parameters for better consistency:
 

docs/prompts.md

@@ -16,6 +16,21 @@ local: true
 ---
 ```
 
+## AsyncClick changes
+
+AsyncClick now async-izes :func:`asyncclick.prompt`. This may require changes
+in your program. We are sorry to have to do this in a minor release, but there
+is no way around this change because the validation callback might be async.
+
+On the positive side, :func:`asyncclick.prompt` gained a new parameter ``blocking``.
+When it is set to `False`, interaction with the user no longer blocks the async
+event loop.
+
+However, this currently interacts badly with interrupting the program, e.g. by
+pressing Control-C. As most programs prompt the user first and run async tasks later,
+the default for ``blocking`` is `True` until we can solve the interrupt problem.
+
+
 (option-prompting)=
 
 ## Option Prompts
@@ -74,14 +89,14 @@ To manually ask for user input, you can use the {func}`prompt` function. By defa
 you can ask for any other type. For instance, you can ask for a valid integer:
 
 ```python
-value = click.prompt('Please enter a valid integer', type=int)
+value = await click.prompt('Please enter a valid integer', type=int)
 ```
 
 Additionally, the type will be determined automatically if a default value is provided. For instance, the following will
 only accept floats:
 
 ```python
-value = click.prompt('Please enter a number', default=42.0)
+value = await click.prompt('Please enter a number', default=42.0)
 ```
 
 ## Optional Prompts

src/asyncclick/termui.py

@@ -93,6 +93,7 @@ async def prompt(
     show_default: bool = True,
     err: bool = False,
     show_choices: bool = True,
+    blocking: bool = True,
 ) -> t.Any:
     """Prompts a user for input.  This is a convenience function that can
     be used to prompt a user for input later.
@@ -120,11 +121,18 @@ async def prompt(
                          For example if type is a Choice of either day or week,
                          show_choices is true and text is "Group by" then the
                          prompt will be "Group by (day, week): ".
+    :param blocking: if `False`, uses a thread to interact with the terminal.
+                     This keeps the event loop running but may cause interesting
+                     effects when interrupted with Control-C. The default
+                     is `True`, but don't depend on it.
 
     Warning: The user interaction is run inside a separate thread, because otherwise
     the call would block the async loop. As a result, behavior when interrupted may be
     sub-optimal.
 
+    .. versionadded:: 8.3
+        (AsyncClick) ``prompt`` is now async; ``blocking`` parameter added.
+
     .. versionadded:: 8.0
         ``confirmation_prompt`` can be a custom string.
 
@@ -156,6 +164,13 @@ def prompt_func(text: str) -> str:
                 echo(None, err=err)
             raise Abort() from None
 
+    if blocking:
+        async def run_prompt_func(text: str) -> str:
+            return prompt_func(text)
+    else:
+        def run_prompt_func(text: str) -> Awaitable[str]:
+            return anyio.to_thread.run_sync(prompt_func, text)
+
     if value_proc is None:
         value_proc = convert_type(type, default)
 
@@ -171,7 +186,7 @@ def prompt_func(text: str) -> str:
 
     while True:
         while True:
-            value = await anyio.to_thread.run_sync(prompt_func, prompt)
+            value = await run_prompt_func(prompt)
             if value:
                 break
             elif default is not None:
@@ -190,7 +205,7 @@ def prompt_func(text: str) -> str:
         if not confirmation_prompt:
             return result
         while True:
-            value2 = await anyio.to_thread.run_sync(prompt_func, confirmation_prompt)
+            value2 = await run_prompt_func(confirmation_prompt)
             is_empty = not value and not value2
             if value2 or is_empty:
                 break