fixes #771

Author: jph00

fastcore/_modidx.py

@@ -743,6 +743,7 @@
                                 'fastcore.xtras.hl_md': ('xtras.html#hl_md', 'fastcore/xtras.py'),
                                 'fastcore.xtras.image_size': ('xtras.html#image_size', 'fastcore/xtras.py'),
                                 'fastcore.xtras.img_bytes': ('xtras.html#img_bytes', 'fastcore/xtras.py'),
+                                'fastcore.xtras.is_async_callable': ('xtras.html#is_async_callable', 'fastcore/xtras.py'),
                                 'fastcore.xtras.is_listy': ('xtras.html#is_listy', 'fastcore/xtras.py'),
                                 'fastcore.xtras.is_namedtuple': ('xtras.html#is_namedtuple', 'fastcore/xtras.py'),
                                 'fastcore.xtras.is_typeddict': ('xtras.html#is_typeddict', 'fastcore/xtras.py'),

fastcore/xtras.py

@@ -15,8 +15,8 @@
            'autostart', 'EventTimer', 'stringfmt_names', 'PartialFormatter', 'partial_format', 'truncstr', 'utc2local',
            'local2utc', 'trace', 'modified_env', 'ContextManagers', 'shufflish', 'console_help', 'hl_md', 'type2str',
            'dataclass_src', 'Unset', 'nullable_dc', 'make_nullable', 'flexiclass', 'asdict', 'vars_pub', 'is_typeddict',
-           'is_namedtuple', 'CachedIter', 'CachedAwaitable', 'reawaitable', 'flexicache', 'time_policy', 'mtime_policy',
-           'timed_cache']
+           'is_namedtuple', 'CachedIter', 'CachedAwaitable', 'reawaitable', 'is_async_callable', 'flexicache',
+           'time_policy', 'mtime_policy', 'timed_cache']
 
 # %% ../nbs/03_xtras.ipynb #3401d507
 from .imports import *
@@ -960,6 +960,14 @@ def reawaitable(func:callable):
     def _f(*args, **kwargs): return CachedAwaitable(func(*args, **kwargs))
     return _f
 
+# %% ../nbs/03_xtras.ipynb #1fc78492
+def is_async_callable(obj):
+    "Check if `obj` is an async callable, handling `partial` wrappers and callable instances"
+    # Implementation from Starlette; Copyright © 2018, Encode OSS Ltd.
+    from asyncio import iscoroutinefunction
+    while isinstance(obj, partial): obj = obj.func
+    return iscoroutinefunction(obj) or (callable(obj) and iscoroutinefunction(obj.__call__))
+
 # %% ../nbs/03_xtras.ipynb #d2b4fe09
 def flexicache(*funcs, maxsize=128):
     "Like `lru_cache`, but customisable with policy `funcs`"

nbs/03_xtras.ipynb

@@ -2261,7 +2261,7 @@
     {
      "data": {
       "text/plain": [
-       "['h', 'g', 'c', 'f', 'e', 'a', 'd', 'b']"
+       "['e', 'b', 'g', 'd', 'h', 'c', 'f', 'a']"
       ]
      },
      "execution_count": null,
@@ -2657,7 +2657,7 @@
     {
      "data": {
       "text/plain": [
-       "'_sKl4z921TkyyYSWEcGSsbQ'"
+       "'_z9sXygihSNeFX55bTEVs3A'"
       ]
      },
      "execution_count": null,
@@ -2752,7 +2752,7 @@
     {
      "data": {
       "text/plain": [
-       "('5ca7845c', '8c7d7247')"
+       "('40e6f9cb', '8c7d7247')"
       ]
      },
      "execution_count": null,
@@ -3504,8 +3504,8 @@
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "Num Events: 9, Freq/sec: 340.6\n",
-      "Most recent:  ▅▃▇▁▅ 268.0 265.5 297.0 225.3 273.3\n"
+      "Num Events: 9, Freq/sec: 344.8\n",
+      "Most recent:  ▅▃▆▁▇ 266.1 261.7 279.1 235.3 283.6\n"
      ]
     }
    ],
@@ -4642,6 +4642,68 @@
     "print(await r)  # \"data\" (no delay)"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "1fc78492",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "#| export\n",
+    "def is_async_callable(obj):\n",
+    "    \"Check if `obj` is an async callable, handling `partial` wrappers and callable instances\"\n",
+    "    # Implementation from Starlette; Copyright © 2018, Encode OSS Ltd.\n",
+    "    from asyncio import iscoroutinefunction\n",
+    "    while isinstance(obj, partial): obj = obj.func\n",
+    "    return iscoroutinefunction(obj) or (callable(obj) and iscoroutinefunction(obj.__call__))"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "c498168d",
+   "metadata": {},
+   "source": [
+    "`is_async_callable` detects whether an object can be called asynchronously. It goes beyond `asyncio.iscoroutinefunction` by also handling `functools.partial`-wrapped async functions (unwrapping through any number of layers) and callable objects whose `__call__` method is a coroutine. The implementation is thanks to [Starlette](https://github.com/encode/starlette)."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "0079316a",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "async def f(): pass\n",
+    "assert is_async_callable(f)\n",
+    "assert is_async_callable(partial(f))\n",
+    "assert not is_async_callable(lambda: None)"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "cfb13929",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "class AsyncObj:\n",
+    "    async def __call__(self): pass\n",
+    "\n",
+    "class SyncObj:\n",
+    "    def __call__(self): pass\n",
+    "\n",
+    "assert is_async_callable(AsyncObj())\n",
+    "assert not is_async_callable(SyncObj())"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "id": "81493a56",
+   "metadata": {},
+   "source": [
+    "### flexicache"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
@@ -4883,13 +4945,7 @@
    ]
   }
  ],
- "metadata": {
-  "kernelspec": {
-   "display_name": "python3",
-   "language": "python",
-   "name": "python3"
-  }
- },
+ "metadata": {},
  "nbformat": 4,
  "nbformat_minor": 5
 }