From d46b8653d96a7e405bd12fa54cc9c51c4946b7a0 Mon Sep 17 00:00:00 2001
From: Yarvin <yavinlecretin@gmail.com>
Date: Mon, 6 Jan 2025 11:59:13 +0100
Subject: [PATCH] - Derive Var and Export for DynGd<T, D>

---
 godot-core/src/obj/dyn_gd.rs               | 27 +++++++++++++++++++++-
 itest/godot/ManualFfiTests.gd              | 19 +++++++++++++++
 itest/rust/src/object_tests/dyn_gd_test.rs | 22 ++++++++++++++++++
 3 files changed, 67 insertions(+), 1 deletion(-)

diff --git a/godot-core/src/obj/dyn_gd.rs b/godot-core/src/obj/dyn_gd.rs
index 96611ea76..db869a06b 100644
--- a/godot-core/src/obj/dyn_gd.rs
+++ b/godot-core/src/obj/dyn_gd.rs
@@ -7,10 +7,11 @@
 
 use crate::builtin::Variant;
 use crate::meta::error::ConvertError;
-use crate::meta::{FromGodot, GodotConvert, ToGodot};
+use crate::meta::{ClassName, FromGodot, GodotConvert, ToGodot};
 use crate::obj::guards::DynGdRef;
 use crate::obj::{bounds, AsDyn, Bounds, DynGdMut, Gd, GodotClass, Inherits};
 use crate::registry::class::try_dynify_object;
+use crate::registry::property::{Export, Var};
 use crate::{meta, sys};
 use std::{fmt, ops};
 
@@ -478,3 +479,27 @@ where
     D: ?Sized + 'static,
 {
 }
+
+impl<T, D> Var for DynGd<T, D>
+where
+    T: GodotClass,
+    D: ?Sized + 'static,
+{
+    fn get_property(&self) -> Self::Via {
+        self.to_godot()
+    }
+
+    fn set_property(&mut self, value: Self::Via) {
+        *self = FromGodot::from_godot(value);
+    }
+}
+
+impl<T, D> Export for DynGd<T, D>
+where
+    T: GodotClass,
+    D: ?Sized + 'static,
+{
+    fn as_node_class() -> Option<ClassName> {
+        Some(T::class_name())
+    }
+}
diff --git a/itest/godot/ManualFfiTests.gd b/itest/godot/ManualFfiTests.gd
index 8eeaa9c95..bc71b71e2 100644
--- a/itest/godot/ManualFfiTests.gd
+++ b/itest/godot/ManualFfiTests.gd
@@ -68,6 +68,25 @@ func test_export():
 	obj.free()
 	node.free()
 
+func test_export_dyn_gd():
+	var dyn_gd_exporter = DynGdExporter.new()
+	# Nodehealth is valid candidate both for `empty` and `second` fields.
+	var node = NodeHealth.new()
+	dyn_gd_exporter.first = node
+	assert_eq(dyn_gd_exporter.first, node)
+	dyn_gd_exporter.second = node
+	assert_eq(dyn_gd_exporter.second, node)
+
+	# RefcHealth is valid candidate for `first` field
+	var refc = RefcHealth.new()
+	dyn_gd_exporter.first = refc
+	assert_eq(dyn_gd_exporter.first, refc)
+	disable_error_messages()
+	dyn_gd_exporter.second = refc # Should fail.
+	enable_error_messages()
+	assert_fail("DynGdExporter.second should only accept NodeHealth if it implements InstanceIdProvider trait")
+
+
 class MockObjGd extends Object:
 	var i: int = 0
 
diff --git a/itest/rust/src/object_tests/dyn_gd_test.rs b/itest/rust/src/object_tests/dyn_gd_test.rs
index 72394acfb..89f4cb004 100644
--- a/itest/rust/src/object_tests/dyn_gd_test.rs
+++ b/itest/rust/src/object_tests/dyn_gd_test.rs
@@ -445,3 +445,25 @@ impl InstanceIdProvider for foreign::NodeHealth {
         self.base().instance_id()
     }
 }
+
+// ----------------------------------------------------------------------------------------------------------------------------------------------
+// Check if DynGd can be properly exported
+
+#[derive(GodotClass)]
+#[class(base=Node)]
+struct DynGdExporter {
+    #[export]
+    first: Option<DynGd<Object, dyn Health>>,
+    #[export]
+    second: Option<DynGd<foreign::NodeHealth, dyn InstanceIdProvider>>,
+}
+
+#[godot_api]
+impl INode for DynGdExporter {
+    fn init(_base: Base<Node>) -> Self {
+        Self {
+            first: None,
+            second: None,
+        }
+    }
+}