Add support for __getattr__

parsl/dataflow/futures.py

@@ -139,9 +139,33 @@ def __getitem__(self, key: Any) -> AppFuture:
 
         return deferred_getitem_app(self, key)
 
+    def __getattr__(self, name: str) -> AppFuture:
+        # hack around circular imports for python_app
+        from parsl.app.app import python_app
+
+        # TODO: it would be nice to avoid redecorating this each time,
+        # which was done to avoid import loops here -- but the DFK
+        # is not defined at import time, and so this decoration needs
+        # to happen at least once per DFK. So perhaps for implementation
+        # simplicity, this redecoration should always happen, as happens
+        # for example with the globus data provider.
+
+        # TODO: this should be run on the same DFK as is executing the
+        # task that is associated with this future. That value isn't
+        # easily available here (although probably the right thing to
+        # do is add it to self.task_def)
+        deferred_getattr_app = python_app(deferred_getattr, executors=['_parsl_internal'])
+
+        return deferred_getattr_app(self, name)
 
 # this needs python_app to be importable, but three's an import loop
 # if so... so hack around it for prototyping.
 # @python_app
 def deferred_getitem(o: Any, k: Any) -> Any:
     return o[k]
+
+# this needs python_app to be importable, but three's an import loop
+# if so... so hack around it for prototyping.
+# @python_app
+def deferred_getattr(o: Any, name: str) -> Any:
+    return getattr(o, name)

parsl/tests/test_python_apps/test_lifted.py

@@ -0,0 +1,54 @@
+from parsl import python_app
+
+
+@python_app
+def returns_a_dict():
+    return {"a": "X", "b": "Y"}
+
+@python_app
+def returns_a_list():
+    return ["X", "Y"]
+
+@python_app
+def returns_a_class():
+    from dataclasses import dataclass
+
+    @dataclass
+    class MyClass:
+        a: str = "X"
+        b: str = "Y"
+
+    return MyClass
+
+def test_returns_a_dict():
+
+    # precondition that returns_a_dict behaves
+    # correctly
+    assert returns_a_dict().result()["a"] == "X"
+
+    # check that the deferred __getitem__ functionality works,
+    # allowing [] to be used on an AppFuture
+    assert returns_a_dict()["a"].result() == "X"
+
+def test_returns_a_list():
+
+    # precondition that returns_a_list behaves
+    # correctly
+    assert returns_a_list().result()[0] == "X"
+
+    # check that the deferred __getitem__ functionality works,
+    # allowing [] to be used on an AppFuture
+    assert returns_a_list()[0].result() == "X"
+
+def test_returns_a_class():
+
+    # precondition that returns_a_class behaves
+    # correctly
+    assert returns_a_class().result().a == "X"
+
+    # check that the deferred __getitem__ functionality works,
+    # allowing [] to be used on an AppFuture
+    assert returns_a_class().a.result() == "X"
+
+    # when the result is not indexable, a sensible error should
+    # appear in the appropriate future