holoviz · philippjfr · Oct 2, 2023 · Oct 2, 2023 · Oct 2, 2023 · Oct 2, 2023
diff --git a/param/parameterized.py b/param/parameterized.py
@@ -173,7 +173,7 @@ def resolve_value(value):
             resolve_value(value.step)
         )
     value = transform_reference(value)
-    if hasattr(value, '_dinfo'):
+    if hasattr(value, '_dinfo') or iscoroutinefunction(value):
         value = eval_function_with_deps(value)
     elif isinstance(value, Parameter):
         value = getattr(value.owner, value.name)
@@ -3567,9 +3567,13 @@ def __param_inheritance(mcs, param_name, param):
                     callables[slot] = default_val
                 else:
                     slot_values[slot] = default_val
-            elif slot == 'allow_refs' and not slot_values[slot]:
+            elif slot == 'allow_refs':
                 # Track Parameters that explicitly declared no refs
-                mcs._param__private.explicit_no_refs.append(param.name)
+                explicit_no_refs = mcs._param__private.explicit_no_refs
+                if param.allow_refs is False:
+                    explicit_no_refs.append(param.name)
+                elif param.allow_refs is True and param.name in explicit_no_refs:
+                    explicit_no_refs.remove(param.name)
 
         # Now set the actual slot values
         for slot, value in slot_values.items():

diff --git a/pyproject.toml b/pyproject.toml
@@ -46,6 +46,7 @@ doc = [
 tests = [
     "coverage[toml]",
     "pytest",
+    "pytest-asyncio",
 ]
 tests-deser = [
     "xlrd",
@@ -56,6 +57,7 @@ tests-deser = [
 ]
 tests-examples = [
     "pytest",
+    "pytest-asyncio",
     "pytest-xdist",
     "nbval",
     "param[examples]",
@@ -218,6 +220,7 @@ filterwarnings = [
   "error",
 ]
 xfail_strict = "true"
+asyncio_mode = "auto"
 
 [tool.coverage.report]
 omit = ["param/version.py"]
diff --git a/tests/conftest.py b/tests/conftest.py
@@ -1,8 +1,17 @@
+import asyncio
+
 import param
 import pytest
 
 param.parameterized.warnings_as_exceptions = True
 
+def async_execute(func):
+    event_loop = asyncio.get_running_loop()
+    if event_loop.is_running():
+        asyncio.create_task(func())
+    else:
+        event_loop.run_until_complete(func())
+    return
 
 @pytest.fixture
 def dataframe():
@@ -12,3 +21,10 @@ def dataframe():
         'float': [3.14, 6.28, 9.42],
         'str': ['A', 'B', 'C']
     }, index=[1, 2, 3], columns=['int', 'float', 'str'])
+
+@pytest.fixture
+def async_executor():
+    old_executor = param.parameterized.async_executor
+    param.parameterized.async_executor = async_execute
+    yield
+    param.parameterized.async_executor = old_executor
diff --git a/tests/testrefs.py b/tests/testrefs.py
@@ -1,3 +1,5 @@
+import asyncio
+
 import param
 import pytest
 
@@ -11,6 +13,15 @@ class Parameters(param.Parameterized):
 
     string_list = param.List(default=[], item_type=str, allow_refs=True, nested_refs=True)
 
+    no_refs = param.Parameter(allow_refs=False)
+
+class Subclass(Parameters):
+
+    no_refs = param.Parameter()
+
+class SubclassOverride(Parameters):
+
+    no_refs = param.Parameter(allow_refs=True)
 
 class Nested(param.Parameterized):
 
@@ -21,6 +32,15 @@ def string(self):
         return self.subobject.string + '!'
 
 
+def test_class_explicit_no_refs():
+    assert Parameters._param__private.explicit_no_refs == ['no_refs']
+
+def test_subclass_explicit_no_refs():
+    assert Subclass._param__private.explicit_no_refs == ['no_refs']
+
+def test_subclass_explicit_no_refs_override():
+    assert SubclassOverride._param__private.explicit_no_refs == []
+
 def test_parameterized_warns_explicit_no_ref():
     class ImplicitRefsParameters(param.Parameterized):
         parameter = param.Parameter(default="string")
@@ -100,3 +120,38 @@ def test_nested_param_method_ref():
     assert p2.string == 'string!'
     p.string = 'new string'
     assert p2.string == 'new string!'
+
+async def test_async_function_ref(async_executor):
+    async def gen_strings():
+        await asyncio.sleep(0.02)
+        return 'string!'
+
+    p = Parameters(string=gen_strings)
+
+    await asyncio.sleep(0.1)
+    assert p.string == 'string!'
+
+async def test_async_bind_ref(async_executor):
+    p = Parameters()
+
+    async def exclaim(string):
+        await asyncio.sleep(0.05)
+        return string + '!'
+
+    p2 = Parameters(string=bind(exclaim, p.param.string))
+    await asyncio.sleep(0.1)
+    assert p2.string == 'string!'
+    p.string = 'new string'
+    await asyncio.sleep(0.1)
+    assert p2.string == 'new string!'
+
+async def test_async_generator_ref(async_executor):
+    async def gen_strings():
+        string = 'string'
+        for i in range(10):
+            yield string + '!' * i
+
+    p = Parameters(string=gen_strings)
+
+    await asyncio.sleep(0.1)
+    assert p.string == 'string!!!!!!!!!'