enable passing list[Arg] to 'inputs' in decorator

Author: tclose

pydra/compose/base/helpers.py

@@ -185,10 +185,15 @@ def extract_function_inputs_and_outputs(
             input_defaults[p.name] = p.default
     if inputs is not None:
         if not isinstance(inputs, dict):
-            raise ValueError(
-                f"Input names ({inputs}) should not be provided when "
-                "wrapping/decorating a function as "
-            )
+            if non_named_args := [
+                i for i in inputs if not isinstance(i, Arg) or i.name is None
+            ]:
+                raise ValueError(
+                    "Only named Arg objects should be provided as inputs (i.e. not names or "
+                    "other objects should not be provided when wrapping/decorating a "
+                    f"function: found {non_named_args} when wrapping/decorating {function!r}"
+                )
+            inputs = {i.name: i for i in inputs}
         if not has_varargs:
             if unrecognised := set(inputs) - set(input_types):
                 raise ValueError(

pydra/compose/tests/test_python_fields.py

@@ -41,6 +41,26 @@ def func(function: ty.Callable) -> ty.Callable:
             return function
 
 
+def test_function_arg_fail2():
+
+    with pytest.raises(
+        ValueError, match="Only named Arg objects should be provided as inputs"
+    ):
+
+        @python.define(inputs=[python.arg(help="an int")])
+        def func(a: int) -> int:
+            return a * 2
+
+
+def test_function_arg_add_help():
+
+    @python.define(inputs=[python.arg(name="a", help="an int")])
+    def func(a: int) -> int:
+        return a * 2
+
+    assert task_fields(func).a.help == "an int"
+
+
 def test_interface_wrap_function_with_default():
     def func(a: int, k: float = 2.0) -> float:
         """Sample function with inputs and outputs"""

pydra/utils/general.py

@@ -21,7 +21,7 @@
 
 logger = logging.getLogger("pydra")
 if ty.TYPE_CHECKING:
-    from pydra.compose.base import Task
+    from pydra.compose.base import Task, Field  # noqa
     from pydra.compose import workflow