Add CallableCustom that devs can use in their GDExtensions

test/src/example.cpp

@@ -15,6 +15,46 @@
 
 using namespace godot;
 
+class MyCallableCustom : public CallableCustom {
+public:
+	virtual uint32_t hash() const {
+		return 27;
+	}
+
+	virtual String get_as_text() const {
+		return "<MyCallableCustom>";
+	}
+
+	static bool compare_equal_func(const CallableCustom *p_a, const CallableCustom *p_b) {
+		return p_a == p_b;
+	}
+
+	virtual CompareEqualFunc get_compare_equal_func() const {
+		return &MyCallableCustom::compare_equal_func;
+	}
+
+	static bool compare_less_func(const CallableCustom *p_a, const CallableCustom *p_b) {
+		return (void *)p_a < (void *)p_b;
+	}
+
+	virtual CompareLessFunc get_compare_less_func() const {
+		return &MyCallableCustom::compare_less_func;
+	}
+
+	bool is_valid() const {
+		return true;
+	}
+
+	virtual ObjectID get_object() const {
+		return ObjectID();
+	}
+
+	virtual void call(const Variant **p_arguments, int p_argcount, Variant &r_return_value, GDExtensionCallError &r_call_error) const {
+		r_return_value = "Hi";
+		r_call_error.error = GDEXTENSION_CALL_OK;
+	}
+};
+
 void ExampleRef::set_id(int p_id) {
 	id = p_id;
 }
@@ -168,6 +208,7 @@ void Example::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("test_callable_mp_retc"), &Example::test_callable_mp_retc);
 	ClassDB::bind_method(D_METHOD("test_callable_mp_static"), &Example::test_callable_mp_static);
 	ClassDB::bind_method(D_METHOD("test_callable_mp_static_ret"), &Example::test_callable_mp_static_ret);
+	ClassDB::bind_method(D_METHOD("test_custom_callable"), &Example::test_custom_callable);
 
 	ClassDB::bind_method(D_METHOD("test_bitfield", "flags"), &Example::test_bitfield);
 
@@ -378,6 +419,10 @@ Callable Example::test_callable_mp_static_ret() const {
 	return callable_mp_static(&Example::unbound_static_method2);
 }
 
+Callable Example::test_custom_callable() const {
+	return Callable(memnew(MyCallableCustom));
+}
+
 void Example::unbound_method1(Object *p_object, String p_string, int p_int) {
 	String test = "unbound_method1: ";
 	test += p_object->get_class();