datasette.utils.check_callable(obj) - refs #2078

datasette/utils/callable.py

@@ -0,0 +1,25 @@
+import asyncio
+import types
+from typing import NamedTuple, Any
+
+
+class CallableStatus(NamedTuple):
+    is_callable: bool
+    is_async_callable: bool
+
+
+def check_callable(obj: Any) -> CallableStatus:
+    if not callable(obj):
+        return CallableStatus(False, False)
+
+    if isinstance(obj, type):
+        # It's a class
+        return CallableStatus(True, False)
+
+    if isinstance(obj, types.FunctionType):
+        return CallableStatus(True, asyncio.iscoroutinefunction(obj))
+
+    if hasattr(obj, "__call__"):
+        return CallableStatus(True, asyncio.iscoroutinefunction(obj.__call__))
+
+    assert False, "obj {} is somehow callable with no __call__ method".format(repr(obj))