From 681f7c3694a1500fec2ef8e8426cdad824508e00 Mon Sep 17 00:00:00 2001
From: "Jonathan B. Coe" <jonathanbcoe@gmail.com>
Date: Wed, 1 Apr 2026 21:12:57 +0100
Subject: [PATCH 1/2] Example of how to add a protocol

---
 CMakeLists.txt   |  7 ++++++-
 demo.h           | 12 ++++++++++++
 protocol_test.cc | 10 ++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 demo.h

diff --git a/CMakeLists.txt b/CMakeLists.txt
index e66d252..b3007c0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -116,6 +116,10 @@ if(XYZ_PROTOCOL_IS_NOT_SUBPROJECT)
       CLASS_NAME C INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}/interface_C.h
       HEADER interface_C.h
       OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/generated/protocol_C.h ${OPT_MANUAL_VTABLE})
+    xyz_generate_protocol(
+      CLASS_NAME Demo INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}/demo.h
+      HEADER demo.h
+      OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/generated/protocol_demo.h ${OPT_MANUAL_VTABLE})
 
     add_custom_target(
       generate_protocols
@@ -123,7 +127,8 @@ if(XYZ_PROTOCOL_IS_NOT_SUBPROJECT)
               ${CMAKE_CURRENT_BINARY_DIR}/generated/protocol_A_virtual.h
               ${CMAKE_CURRENT_BINARY_DIR}/generated/protocol_A_manual.h
               ${CMAKE_CURRENT_BINARY_DIR}/generated/protocol_B.h
-              ${CMAKE_CURRENT_BINARY_DIR}/generated/protocol_C.h)
+              ${CMAKE_CURRENT_BINARY_DIR}/generated/protocol_C.h
+              ${CMAKE_CURRENT_BINARY_DIR}/generated/protocol_demo.h)
 
     xyz_add_test(
       NAME
diff --git a/demo.h b/demo.h
new file mode 100644
index 0000000..c357b5f
--- /dev/null
+++ b/demo.h
@@ -0,0 +1,12 @@
+#ifndef XYZ_PROTOCOL_DEMO_H
+#define XYZ_PROTOCOL_DEMO_H
+
+namespace xyz {
+
+struct Demo {
+  int operator()(int) const;
+};
+
+}  // namespace xyz
+
+#endif  // XYZ_PROTOCOL_DEMO_H
diff --git a/protocol_test.cc b/protocol_test.cc
index eae1934..0a08439 100644
--- a/protocol_test.cc
+++ b/protocol_test.cc
@@ -30,6 +30,7 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 #include "generated/protocol_A.h"
 #include "generated/protocol_B.h"
 #include "generated/protocol_C.h"
+#include "generated/protocol_demo.h"
 #include "tracking_allocator.h"
 
 namespace {
@@ -626,4 +627,13 @@ TEST(ProtocolViewTest, ViewMoveIsStandard) {
   EXPECT_EQ(view2.name(), "move_test");
 }
 
+struct Demoic {
+  int operator()(int x) const { return x * 2; }
+};
+
+TEST(ProtocolDemoTest, DemoFunction) {
+  xyz::protocol<xyz::Demo> demo(std::in_place_type<Demoic>);
+  EXPECT_EQ(demo(5), 10);
+}
+
 }  // namespace

From 75a2f08a8303d6fa635f4ba2faa8e79c56da1027 Mon Sep 17 00:00:00 2001
From: "Jonathan B. Coe" <jonathanbcoe@gmail.com>
Date: Wed, 1 Apr 2026 21:22:34 +0100
Subject: [PATCH 2/2] Fix for operator() which needs mangling (for now)

---
 demo.h           | 2 +-
 protocol_test.cc | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/demo.h b/demo.h
index c357b5f..f970e5f 100644
--- a/demo.h
+++ b/demo.h
@@ -4,7 +4,7 @@
 namespace xyz {
 
 struct Demo {
-  int operator()(int) const;
+  int call(int) const;
 };
 
 }  // namespace xyz
diff --git a/protocol_test.cc b/protocol_test.cc
index 0a08439..b80437d 100644
--- a/protocol_test.cc
+++ b/protocol_test.cc
@@ -628,12 +628,12 @@ TEST(ProtocolViewTest, ViewMoveIsStandard) {
 }
 
 struct Demoic {
-  int operator()(int x) const { return x * 2; }
+  int call(int x) const { return x * 2; }
 };
 
 TEST(ProtocolDemoTest, DemoFunction) {
   xyz::protocol<xyz::Demo> demo(std::in_place_type<Demoic>);
-  EXPECT_EQ(demo(5), 10);
+  EXPECT_EQ(demo.call(5), 10);
 }
 
 }  // namespace