Support async functions and methods in CLI

CHANGELOG.rst

@@ -17,6 +17,8 @@ v4.31.0 (2024-06-??)
 
 Added
 ^^^^^
+- Support async functions and methods in ``CLI`` (`#531
+  <https://github.com/omni-us/jsonargparse/pull/531>`__).
 - Support for ``Protocol`` types only accepting exact matching signature of
   public methods (`#526
   <https://github.com/omni-us/jsonargparse/pull/526>`__).

jsonargparse/_cli.py

@@ -92,8 +92,8 @@ def CLI(
             deprecation_warning_cli_return_parser()
             return parser
         cfg = parser.parse_args(args)
-        cfg_init = parser.instantiate_classes(cfg)
-        return _run_component(components, cfg_init)
+        init = parser.instantiate_classes(cfg)
+        return _run_component(components, init)
 
     elif isinstance(components, list):
         components = {c.__name__: c for c in components}
@@ -192,12 +192,13 @@ def _add_component_to_parser(
 
 def _run_component(component, cfg):
     cfg.pop("config", None)
-    if not inspect.isclass(component):
-        return component(**cfg)
     subcommand = cfg.pop("subcommand")
-    if not subcommand:
-        return component(**cfg)
-    subcommand_cfg = cfg.pop(subcommand, {})
-    subcommand_cfg.pop("config", None)
-    component_obj = component(**cfg)
-    return getattr(component_obj, subcommand)(**subcommand_cfg)
+    if inspect.isclass(component) and subcommand:
+        subcommand_cfg = cfg.pop(subcommand, {})
+        subcommand_cfg.pop("config", None)
+        component_obj = component(**cfg)
+        component = getattr(component_obj, subcommand)
+        cfg = subcommand_cfg
+    if inspect.iscoroutinefunction(component):
+        return __import__("asyncio").run(component(**cfg))
+    return component(**cfg)

jsonargparse_tests/test_cli.py

@@ -1,12 +1,13 @@
 from __future__ import annotations
 
+import asyncio
 import os
 import sys
 from contextlib import redirect_stderr, redirect_stdout, suppress
 from dataclasses import asdict, dataclass
 from io import StringIO
 from pathlib import Path
-from typing import Optional
+from typing import Callable, Optional
 from unittest.mock import patch
 
 import pytest
@@ -535,3 +536,44 @@ def test_final_and_subclass_type_config_file(tmp_cwd):
 
     out = CLI(run_bf, args=["--config=config.yaml"])
     assert "a yaml" == out
+
+
+# async tests
+
+
+async def run_async(time: float = 0.1):
+    await asyncio.sleep(time)
+    return "done"
+
+
+def test_async_function():
+    assert "done" == CLI(run_async, args=["--time=0.0"])
+
+
+class AsyncMethod:
+    def __init__(self, time: float = 0.1, require_async: bool = False):
+        self.time = time
+        if require_async:
+            self.loop = asyncio.get_event_loop()
+
+    async def run(self):
+        await asyncio.sleep(self.time)
+        return "done"
+
+
+def test_async_method():
+    assert "done" == CLI(AsyncMethod, args=["--time=0.0", "run"])
+
+
+async def run_async_instance(cls: Callable[[], AsyncMethod]):
+    return await cls().run()
+
+
+def test_async_instance():
+    config = {
+        "cls": {
+            "class_path": f"{__name__}.AsyncMethod",
+            "init_args": {"time": 0.0, "require_async": True},
+        }
+    }
+    assert "done" == CLI(run_async_instance, args=[f"--config={config}"])