From 9969c36410b0cb5422406288e665f9861aab9d89 Mon Sep 17 00:00:00 2001
From: David Hale <dhale@caltech.edu>
Date: Wed, 23 Sep 2026 13:50:28 -0700
Subject: [PATCH 1/2] moves the registration TU out of the core library into
 the final targets

the shared library no longer forces a choice of interface.
camerad and the python module each link exactly one registration.
---
 camerad/CMakeLists.txt | 7 ++++++-
 python/CMakeLists.txt  | 1 +
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/camerad/CMakeLists.txt b/camerad/CMakeLists.txt
index aa72d47..88380c0 100644
--- a/camerad/CMakeLists.txt
+++ b/camerad/CMakeLists.txt
@@ -119,11 +119,15 @@ endif()
 
 # ----------------------------------------------------------------------------
 # Camera Interface Base
+#
+# The registration translation unit, and any instrument sources, are
+# deliberately not part of this library. They are compiled into the final
+# targets below, so linking this library never forces a choice of interface
+# and the final target alone determines which registration is linked.
 # ----------------------------------------------------------------------------
 list (APPEND INTERFACE_SOURCES
   ${CAMERAD_DIR}/camera_interface.cpp
   ${CAMERAD_DIR}/image_process.cpp
-  ${INSTRUMENT_SOURCES}
   )
 add_library(${INTERFACE_TARGET} ${INTERFACE_SOURCES})
 target_link_libraries(${INTERFACE_TARGET}
@@ -164,6 +168,7 @@ find_package(Threads)
 add_executable(camerad
   ${CAMERAD_DIR}/camerad.cpp
   ${CAMERAD_DIR}/camera_server.cpp
+  ${INSTRUMENT_SOURCES}
   )
 
 # ----------------------------------------------------------------------------
diff --git a/python/CMakeLists.txt b/python/CMakeLists.txt
index 6d4e3a2..18efff1 100644
--- a/python/CMakeLists.txt
+++ b/python/CMakeLists.txt
@@ -29,6 +29,7 @@ find_package(pybind11 CONFIG REQUIRED)
 
 pybind11_add_module(camera_interface
   ${PROJECT_BASE_DIR}/python/camera_interface_module.cpp
+  ${INSTRUMENT_SOURCES}
 )
 
 target_include_directories(camera_interface PRIVATE

From 418366ddc6c54f8ac0f31806df2723704d2a3085 Mon Sep 17 00:00:00 2001
From: David Hale <dhale@caltech.edu>
Date: Wed, 23 Sep 2026 16:53:44 -0700
Subject: [PATCH 2/2] builds the instrument implementation once, into an object
 library

---
 camerad/CMakeLists.txt | 28 ++++++++++++++++++++++------
 python/CMakeLists.txt  |  3 ++-
 2 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/camerad/CMakeLists.txt b/camerad/CMakeLists.txt
index 88380c0..681f56f 100644
--- a/camerad/CMakeLists.txt
+++ b/camerad/CMakeLists.txt
@@ -117,13 +117,16 @@ else()
   endif()
 endif()
 
+# ----------------------------------------------------------------------------
+# Separate the registration TU from the instrument implementation so that
+# the registration is compiled into the final target.
+# ----------------------------------------------------------------------------
+set (INSTRUMENT_REGISTRATION ${INSTRUMENT_SOURCES})
+list (FILTER INSTRUMENT_REGISTRATION INCLUDE REGEX "_interface_factory\\.cpp$")
+list (FILTER INSTRUMENT_SOURCES EXCLUDE REGEX "_interface_factory\\.cpp$")
+
 # ----------------------------------------------------------------------------
 # Camera Interface Base
-#
-# The registration translation unit, and any instrument sources, are
-# deliberately not part of this library. They are compiled into the final
-# targets below, so linking this library never forces a choice of interface
-# and the final target alone determines which registration is linked.
 # ----------------------------------------------------------------------------
 list (APPEND INTERFACE_SOURCES
   ${CAMERAD_DIR}/camera_interface.cpp
@@ -136,6 +139,18 @@ target_link_libraries(${INTERFACE_TARGET}
                       )
 target_include_directories(${INTERFACE_TARGET} PUBLIC ${INTERFACE_INCLUDES})
 
+# ----------------------------------------------------------------------------
+# instrument implementation, if any.
+# objects shared by the final targets, not depended on as a library
+# ----------------------------------------------------------------------------
+if (INSTRUMENT_SOURCES)
+  add_library(instrument_obj OBJECT ${INSTRUMENT_SOURCES})
+  target_link_libraries(instrument_obj ${INTERFACE_TARGET})
+  set (INSTRUMENT_OBJECTS $<TARGET_OBJECTS:instrument_obj>)
+else()
+  set (INSTRUMENT_OBJECTS "")
+endif()
+
 # ----------------------------------------------------------------------------
 # External libraries, such as FITS, etc.
 # ----------------------------------------------------------------------------
@@ -168,7 +183,8 @@ find_package(Threads)
 add_executable(camerad
   ${CAMERAD_DIR}/camerad.cpp
   ${CAMERAD_DIR}/camera_server.cpp
-  ${INSTRUMENT_SOURCES}
+  ${INSTRUMENT_REGISTRATION}
+  ${INSTRUMENT_OBJECTS}
   )
 
 # ----------------------------------------------------------------------------
diff --git a/python/CMakeLists.txt b/python/CMakeLists.txt
index 18efff1..eabac89 100644
--- a/python/CMakeLists.txt
+++ b/python/CMakeLists.txt
@@ -29,7 +29,8 @@ find_package(pybind11 CONFIG REQUIRED)
 
 pybind11_add_module(camera_interface
   ${PROJECT_BASE_DIR}/python/camera_interface_module.cpp
-  ${INSTRUMENT_SOURCES}
+  ${INSTRUMENT_REGISTRATION}
+  ${INSTRUMENT_OBJECTS}
 )
 
 target_include_directories(camera_interface PRIVATE