Support @Property getters for warp.struct

Signed-off-by: Alexandre Ghelfi <[email protected]>

Author: Ghelfi

warp/_src/codegen.py

@@ -460,6 +460,7 @@ def __init__(self, key: str, cls: type, module: warp._src.context.Module):
         self.cls = cls
         self.module = module
         self.vars: dict[str, Var] = {}
+        self.properties: dict[str, warp._src.context.Function] = {}
 
         if isinstance(self.cls, Sequence):
             raise RuntimeError("Warp structs must be defined as base classes")
@@ -482,6 +483,12 @@ def __init__(self, key: str, cls: type, module: warp._src.context.Module):
                     warp.init()
                 fields.append((label, var.type._type_))
 
+        # Collect properties, but postpone Function creation until after native_name is set
+        property_members = []
+        for name, item in inspect.getmembers(self.cls):
+            if isinstance(item, property):
+                property_members.append((name, item))
+
         class StructType(ctypes.Structure):
             # if struct is empty, add a dummy field to avoid launch errors on CPU device ("ffi_prep_cif failed")
             _fields_ = fields or [("_dummy_", ctypes.c_byte)]
@@ -502,12 +509,51 @@ class StructType(ctypes.Structure):
             if isinstance(type_hint, Struct):
                 ch.update(type_hint.hash)
 
-        self.hash = ch.digest()
+        # Hash property names (to ensure layout/identity stability if names change)
+        for name, _ in property_members:
+            ch.update(bytes(name, "utf-8"))
 
+        self.hash = ch.digest()
         # generate unique identifier for structs in native code
         hash_suffix = f"{self.hash.hex()[:8]}"
         self.native_name = f"{self.key}_{hash_suffix}"
 
+        # Extract properties and create Functions
+        # self.native_name is now defined, so Function() can resolve 'self' type code.
+        for name, item in property_members:
+            # We currently support only getters
+            if item.fset is not None:
+                raise TypeError("Struct properties with setters are not supported")
+            if item.fdel is not None:
+                raise TypeError("Struct properties with deleters are not supported")
+            getter = item.fget
+            # We need to add 'self' as the first argument, with the type of the struct itself.
+            # This allows overload resolution to match the struct instance to the 'self' argument.
+            if not hasattr(getter, "__annotations__"):
+                getter.__annotations__ = {}
+
+            # Find the name of the first argument (conventionally 'self')
+            argspec = get_full_arg_spec(getter)
+            if len(argspec.args) > 0:
+                self_arg = argspec.args[0]
+                getter.__annotations__[self_arg] = self
+
+            # Create the Warp Function.
+            # We pass 'func=getter' so that input_types and return_types are inferred.
+            # We set 'namespace=""' and a unique 'native_func' to generate a free function
+            # in C++ that takes the struct as the first argument (e.g., StructName_propName(struct_inst)).
+            p_func = warp._src.context.Function(
+                func=getter,
+                key=f"{self.key}.{name}",
+                namespace="",
+                module=module,
+            )
+
+            # Ensure the C++ function name is unique and predictable
+            p_func.native_func = f"{self.native_name}_{name}"
+
+            self.properties[name] = p_func
+
         # create default constructor (zero-initialize)
         self.default_constructor = warp._src.context.Function(
             func=None,
@@ -2260,6 +2306,11 @@ def emit_Attribute(adj, node):
                 else:
                     return adj.add_builtin_call("transform_get_rotation", [aggregate])
 
+            elif isinstance(aggregate_type, Struct) and node.attr in aggregate_type.properties:
+                # property access
+                prop = aggregate_type.properties[node.attr]
+                return adj.add_call(prop, (aggregate,), {}, {})
+
             else:
                 attr_var = aggregate_type.vars[node.attr]
 

warp/tests/test_struct.py

@@ -896,6 +896,53 @@ def test_nested_vec_assignment(self):
 )
 
 
+@wp.struct
+class StructWithProperty:
+    value: float
+
+    @property
+    def neg_value(self) -> float:
+        return -self.value
+
+
+@wp.kernel
+def kernel_struct_property(s: StructWithProperty, out: wp.array(dtype=float)):
+    out[0] = s.neg_value
+
+
+def test_struct_property(test, device):
+    """Tests that structs with properties (getters) are supported."""
+    s = StructWithProperty()
+    s.value = 42.0
+
+    out = wp.zeros(1, dtype=float, device=device)
+
+    wp.launch(kernel_struct_property, dim=1, inputs=[s, out], device=device)
+
+    assert_np_equal(out.numpy(), np.array([-42.0]))
+
+
+def test_struct_property_with_setter(test, device):
+    """Tests that structs with properties (setters) are not supported."""
+    with test.assertRaisesRegex(TypeError, "Struct properties with setters are not supported"):
+
+        @wp.struct
+        class StructWithPropertySetter:
+            value: float
+
+            @property
+            def neg_value(self) -> float:
+                return -self.value
+
+            @neg_value.setter
+            def neg_value(self, value: float):
+                self.value = -value
+
+
+add_function_test(TestStruct, "test_struct_property", test_struct_property, devices=devices)
+add_function_test(TestStruct, "test_struct_property_with_setter", test_struct_property_with_setter, devices=devices)
+
+
 if __name__ == "__main__":
     wp.clear_kernel_cache()
     unittest.main(verbosity=2)