gazebosim · mjcarroll · Oct 11, 2023 · Oct 2, 2023 · Oct 4, 2023
@@ -25,34 +25,49 @@ gz_configure_project(VERSION_SUFFIX
 #============================================================================
 
 # Cross-compilation related options
-# In a cross-compilation scenario, it is possible that the gz_msgs_gen
+# In a cross-compilation scenario, it is possible that the 
+# ${PROJECT_NAME}_protoc_plugin
 # generator compiled for the target machine cannot be used to generate
-# the C++ code corresponding to the .proto definition. For this scenario,
-# the following two options can be used as follows.
+# the C++ code corresponding to the .proto definition.
+# Similarly, it is possible that Python3::Interpreter and protobuf::protoc
+# found via find_package are not executable that can be run during the build.
+# To avoid, that the following options can be used as follows.
 # First of all, gz-msgs is compiled targeting the host machine, and in the
-# build targeting the host, the INSTALL_GZ_MSGS_GEN_EXECUTABLE option is
-# enabled:
-# > cmake -DINSTALL_GZ_MSGS_GEN_EXECUTABLE:BOOL=ON ..
-# ensuring that the gz_msgs_gen is installed in
-# <host_install_prefix>/bin/gz_msgs_gen . Then, the same version of gz-msgs
+# build targeting the host, ensuring that the ${PROJECT_NAME}_protoc_plugin
+# is installed in <host_install_prefix>/bin/${PROJECT_NAME}_protoc_plugin . 
+# Then, the same version of gz-msgs
 # can be cross-compiled, and in the cross-compilation build the location of the
-# host gz_msgs_gen is specified via the GZ_MSGS_GEN_EXECUTABLE
-# CMake cache variable:
-# > cmake -GZ_MSGS_GEN_EXECUTABLE=<host_install_prefix>/bin/gz_msgs_gen ..
+# host gz_msgs_gen is specified via the GZ_MSGS_GEN_EXECUTABLE CMake option.
+# Similarly to gz-msgs, also a copy of protoc and of the Python interpreter need
+# to be installed in the host at <host_install_prefix>/bin, and they can be passed
+# to the build appropriate CMake options:
+# > cmake -Dgz-msgs<MajVer>_PROTO_GENERATOR_PLUGIN=gz-msgs<MajVer>_protoc_plugin
+# >       -Dgz-msgs<MajVer>_PROTOC_EXECUTABLE=<host_install_prefix>/bin/protoc
+# >       -Dgz-msgs<MajVer>_PYTHON_INTERPRETER=<host_install_prefix>/bin/python 
+# >        ..
+# In case the gz-msgs CMake functions are used also in downstream projects, 
+# the same variables can be passed when configuring the downsream projects.
 
-option(
-  INSTALL_GZ_MSGS_GEN_EXECUTABLE
-  "Install the gz_msgs_gen executable."
-  OFF)
+set(
+  ${PROJECT_NAME}_PROTO_GENERATOR_PLUGIN
+  "${PROJECT_NAME}_protoc_plugin"
+  CACHE STRING
+  "gz_msgs_gen executable used in the gz-msgs CMake functions.")
+mark_as_advanced(${PROJECT_NAME}_PROTO_GENERATOR_PLUGIN)
 
-mark_as_advanced(INSTALL_GZ_MSGS_GEN_EXECUTABLE)
+set(
+  ${PROJECT_NAME}_PROTOC_EXECUTABLE
+  protobuf::protoc
+  CACHE STRING
+  "protoc target or executable used in the gz-msgs CMake functions.")
+mark_as_advanced(${PROJECT_NAME}_PROTOC_EXECUTABLE)
 
 set(
-  GZ_MSGS_GEN_EXECUTABLE
-  "$<TARGET_FILE:gz_msgs_gen>"
+  ${PROJECT_NAME}_PYTHON_INTERPRETER
+  Python3::Interpreter
   CACHE STRING
-  "gz_msgs_gen executable used in the gz_msgs_protoc CMake function.")
-mark_as_advanced(GZ_MSGS_GEN_EXECUTABLE)
+  "python target or executable used in the gz-msgs CMake functions.")
+mark_as_advanced(${PROJECT_NAME}_PYTHON_INTERPRETER)
 
 # Python interfaces vars
 option(USE_SYSTEM_PATHS_FOR_PYTHON_INSTALLATION

@@ -6,7 +6,7 @@
 # One value arguments:
 #   FACTORY_GEN_SCRIPT  - Location of the factory generator script
 #   PROTO_PACKAGE       - Protobuf package the file belongs to (e.g. "gz.msgs")
-#   PROTOC_EXEC         - Path to protoc
+#   PYTHON_INTERPRETER  - Target or path to the Python interpreter to use to execute the generator script
 #   OUTPUT_CPP_DIR      - Path where C++ files are saved
 #   OUTPUT_CPP_HH_VAR   - A CMake variable name containing a list that the C++ headers should be appended to
 #   OUTPUT_CPP_CC_VAR   - A Cmake variable name containing a list that the C++ sources should be appended to
@@ -18,13 +18,19 @@ function(gz_msgs_factory)
   set(oneValueArgs
     FACTORY_GEN_SCRIPT
     PROTO_PACKAGE
+    PYTHON_INTERPRETER
     OUTPUT_CPP_DIR
     OUTPUT_CPP_HH_VAR
     OUTPUT_CPP_CC_VAR)
   set(multiValueArgs INPUT_PROTOS PROTO_PATH)
 
   cmake_parse_arguments(gz_msgs_factory "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
 
+  # Default values for optional parameters
+  if (NOT DEFINED gz_msgs_factory_PYTHON_INTERPRETER)
+    set(gz_msgs_factory_PYTHON_INTERPRETER Python3::Interpreter)
+  endif()
+
   _gz_msgs_proto_pkg_to_path(${gz_msgs_factory_PROTO_PACKAGE} proto_package_dir)
 
   set(output_header "${gz_msgs_factory_OUTPUT_CPP_DIR}/${proto_package_dir}/MessageTypes.hh")
@@ -57,7 +63,7 @@ function(gz_msgs_factory)
 
   add_custom_command(
     OUTPUT ${output_files}
-    COMMAND Python3::Interpreter
+    COMMAND ${gz_msgs_factory_PYTHON_INTERPRETER}
     ARGS ${gz_msgs_factory_FACTORY_GEN_SCRIPT} ${GENERATE_ARGS}
     DEPENDS
       ${depends_index}

@@ -2,6 +2,7 @@
 # The implementation of gz_msgs_generate_messages
 # Options:
 # One value arguments:
+#   PYTHON_INTERPRETER  - Target or path to the python interpreter used
 #   PROTO_PACKAGE       - Protobuf package the file belongs to (e.g. "gz.msgs")
 #   MSGS_GEN_SCRIPT     - Location of the messge generator script
 #   GZ_PROTOC_PLUGIN    - Location of the gazebo generator plugin
@@ -20,6 +21,8 @@ function(gz_msgs_generate_messages_impl)
   set(options "")
   set(oneValueArgs
     # Inputs
+    PYTHON_INTERPRETER
+    PROTOC_EXEC
     PROTO_PACKAGE MSGS_GEN_SCRIPT GZ_PROTOC_PLUGIN FACTORY_GEN_SCRIPT PROTO_PATH
     DEPENDENCY_DESCRIPTIONS
     DLLEXPORT_DECL
@@ -33,6 +36,15 @@ function(gz_msgs_generate_messages_impl)
   set(multiValueArgs INPUT_PROTOS)
 
   cmake_parse_arguments(generate_messages "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
+
+  # Default values for optional parameters
+  if (NOT DEFINED generate_messages_PYTHON_INTERPRETER)
+    set(generate_messages_PYTHON_INTERPRETER Python3::Interpreter)
+  endif()
+  if (NOT DEFINED generate_messages_PROTOC_EXEC)
+    set(generate_messages_PROTOC_EXEC protobuf::protoc)
+  endif()
+
   _gz_msgs_proto_pkg_to_string(${generate_messages_PROTO_PACKAGE} gen_dir)
   _gz_msgs_proto_pkg_to_path(${generate_messages_PROTO_PACKAGE} proto_package_dir)
   set(output_directory ${generate_messages_OUTPUT_DIRECTORY})
@@ -42,14 +54,16 @@ function(gz_msgs_generate_messages_impl)
 
   foreach(proto_file ${generate_messages_INPUT_PROTOS})
     gz_msgs_protoc(
+      PYTHON_INTERPRETER
+        ${generate_messages_PYTHON_INTERPRETER}
       MSGS_GEN_SCRIPT
         ${generate_messages_MSGS_GEN_SCRIPT}
       PROTO_PACKAGE
         ${generate_messages_PROTO_PACKAGE}
       INPUT_PROTO
         ${proto_file}
       PROTOC_EXEC
-        protobuf::protoc
+        ${generate_messages_PROTOC_EXEC}
       GZ_PROTOC_PLUGIN
         ${generate_messages_GZ_PROTOC_PLUGIN}
       PROTO_PATH
@@ -81,6 +95,8 @@ function(gz_msgs_generate_messages_impl)
   endforeach()
 
   gz_msgs_factory(
+    PYTHON_INTERPRETER
+      ${generate_messages_PYTHON_INTERPRETER}
     FACTORY_GEN_SCRIPT
       ${generate_messages_FACTORY_GEN_SCRIPT}
     PROTO_PACKAGE
@@ -130,6 +146,7 @@ endfunction()
 ##################################################
 # Options:
 # One value arguments:
+#   PROTOC_EXEC         - protoc target or executable to use
 #   PROTO_PATH          - Base directory of the proto files
 #   DEPENDENCY_DESCRIPTIONS - Variable containing all depedency description files
 #   OUTPUT_DIRECTORY - Directory of output gz_desc file
@@ -140,6 +157,7 @@ function(gz_msgs_generate_desc_impl)
   set(options "")
   set(oneValueArgs
     # Inputs
+    PROTOC_EXEC
     PROTO_PATH
     DEPENDENCY_DESCRIPTIONS
     OUTPUT_DIRECTORY
@@ -148,6 +166,10 @@ function(gz_msgs_generate_desc_impl)
 
   cmake_parse_arguments(generate_messages "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
 
+  if (NOT DEFINED generate_messages_PROTOC_EXEC)
+    set(generate_messages_PROTOC_EXEC protobuf::protoc)
+  endif()
+
   set(ARGS)
   list(APPEND ARGS -I${generate_messages_PROTO_PATH})
   list(APPEND ARGS --descriptor_set_out=${generate_messages_OUTPUT_FILENAME})
@@ -161,7 +183,7 @@ function(gz_msgs_generate_desc_impl)
 
   add_custom_command(
     OUTPUT ${generate_messages_OUTPUT_FILENAME}
-    COMMAND protobuf::protoc
+    COMMAND ${generate_messages_PROTOC_EXEC}
     ARGS ${ARGS}
     DEPENDS ${generate_messages_INPUT_PROTOS}
     COMMENT "Generating descriptor set"
@@ -175,6 +197,8 @@ endfunction()
 #   TARGET              - Target (static library) to create
 #   PROTO_PACKAGE       - Protobuf package the file belongs to (e.g. "gz.msgs")
 #   MSGS_GEN_SCRIPT     - Location of the messge generator script
+#   PYTHON_INTERPRETER  - Target or path to the python interpreter used
+#   PROTOC_EXEC         - Protoc target or executable to use
 #   GZ_PROTOC_PLUGIN    - Location of the gazebo generator plugin
 #   FACTORY_GEN_SCRIPT  - Location of the factory generator script
 #   MSGS_LIB            - gz-msgs library to link to
@@ -186,7 +210,7 @@ endfunction()
 #                         that depend on gz-msgs
 function(gz_msgs_generate_messages_lib)
   set(options "")
-  set(oneValueArgs TARGET PROTO_PACKAGE MSGS_GEN_SCRIPT GZ_PROTOC_PLUGIN FACTORY_GEN_SCRIPT MSGS_LIB PROTO_PATH)
+  set(oneValueArgs TARGET PROTO_PACKAGE MSGS_GEN_SCRIPT PYTHON_INTERPRETER PROTOC_EXEC GZ_PROTOC_PLUGIN FACTORY_GEN_SCRIPT MSGS_LIB PROTO_PATH)
   set(multiValueArgs INPUT_PROTOS DEPENDENCIES)
 
   cmake_parse_arguments(generate_messages "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
@@ -205,9 +229,19 @@ function(gz_msgs_generate_messages_lib)
     list(APPEND depends_msgs_desc ${msgs_desc_file})
   endforeach()
 
+  # Default values for optional parameters
+  if (NOT DEFINED generate_messages_PYTHON_INTERPRETER)
+    set(generate_messages_PYTHON_INTERPRETER Python3::Interpreter)
+  endif()
+  if (NOT DEFINED generate_messages_PROTOC_EXEC)
+    set(generate_messages_PROTOC_EXEC protobuf::protoc)
+  endif()
+
   gz_msgs_generate_messages_impl(
     PROTO_PACKAGE ${generate_messages_PROTO_PACKAGE}
     MSGS_GEN_SCRIPT ${generate_messages_MSGS_GEN_SCRIPT}
+    PYTHON_INTERPRETER ${generate_messages_PYTHON_INTERPRETER}
+    PROTOC_EXEC ${generate_messages_PROTOC_EXEC}
     GZ_PROTOC_PLUGIN ${generate_messages_GZ_PROTOC_PLUGIN}
     FACTORY_GEN_SCRIPT ${generate_messages_FACTORY_GEN_SCRIPT}
     PROTO_PATH ${generate_messages_PROTO_PATH}
@@ -221,6 +255,7 @@ function(gz_msgs_generate_messages_lib)
   )
 
   gz_msgs_generate_desc_impl(
+    PROTOC_EXEC ${generate_messages_PROTOC_EXEC}
     INPUT_PROTOS ${generate_messages_INPUT_PROTOS}
     PROTO_PATH ${generate_messages_PROTO_PATH}
     DEPENDENCY_DESCRIPTIONS ${depends_msgs_desc}

@@ -4,6 +4,7 @@
 #   GENERATE_CPP        - generates c++ code for the message if specified
 #   GENERATE_PYTHON     - generates python code for the message if specified
 # One value arguments:
+#   PYTHON_INTERPRETER  - Target or path to the Python interpreter to use to run generation scripts
 #   MSGS_GEN_SCRIPT     - Path to the message generation python script
 #   PROTO_PACKAGE       - Protobuf package the file belongs to (e.g. "gz.msgs")
 #   PROTOC_EXEC         - Path to protoc
@@ -22,6 +23,7 @@
 function(gz_msgs_protoc)
   set(options GENERATE_CPP GENERATE_PYTHON)
   set(oneValueArgs
+    PYTHON_INTERPRETER
     MSGS_GEN_SCRIPT
     PROTO_PACKAGE
     PROTOC_EXEC
@@ -38,6 +40,13 @@ function(gz_msgs_protoc)
 
   cmake_parse_arguments(gz_msgs_protoc "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
 
+  if (NOT DEFINED gz_msgs_protoc_PYTHON_INTERPRETER)
+    set(gz_msgs_protoc_PYTHON_INTERPRETER Python3::Interpreter)
+  endif()
+  if (NOT DEFINED gz_msgs_protoc_PROTOC_EXEC)
+    set(gz_msgs_protoc_PROTOC_EXEC protobuf::protoc)
+  endif()
+
   get_filename_component(ABS_FIL ${gz_msgs_protoc_INPUT_PROTO} ABSOLUTE)
   get_filename_component(FIL_WE ${gz_msgs_protoc_INPUT_PROTO} NAME_WE)
 
@@ -85,8 +94,14 @@ function(gz_msgs_protoc)
     set(${gz_msgs_protoc_OUTPUT_PYTHON_VAR} ${${gz_msgs_protoc_OUTPUT_PYTHON_VAR}} PARENT_SCOPE)
   endif()
 
+  if(TARGET ${gz_msgs_protoc_PROTOC_EXEC})
+    set(gz_msgs_protoc_PROTOC_EXEC_FILE_ABS_PATH "$<TARGET_FILE:${gz_msgs_protoc_PROTOC_EXEC}>")
+  else()
+    set(gz_msgs_protoc_PROTOC_EXEC_FILE_ABS_PATH ${gz_msgs_protoc_PROTOC_EXEC})
+  endif()
+
   set(GENERATE_ARGS
-      --protoc-exec "$<TARGET_FILE:${gz_msgs_protoc_PROTOC_EXEC}>"
+      --protoc-exec "${gz_msgs_protoc_PROTOC_EXEC_FILE_ABS_PATH}"
       --gz-generator-bin "${gz_msgs_protoc_GZ_PROTOC_PLUGIN}"
       --proto-path "${gz_msgs_protoc_PROTO_PATH}"
       --input-path "${ABS_FIL}"
@@ -118,7 +133,7 @@ function(gz_msgs_protoc)
 
   add_custom_command(
     OUTPUT ${output_files}
-    COMMAND Python3::Interpreter
+    COMMAND ${gz_msgs_protoc_PYTHON_INTERPRETER}
     ARGS ${gz_msgs_protoc_MSGS_GEN_SCRIPT} ${GENERATE_ARGS}
     DEPENDS
       ${ABS_FIL}

@@ -26,13 +26,23 @@ include(${PROJECT_SOURCE_DIR}/cmake/gz_msgs_generate.cmake)
 include(${PROJECT_SOURCE_DIR}/cmake/gz_msgs_protoc.cmake)
 include(${PROJECT_SOURCE_DIR}/cmake/gz_msgs_string_utils.cmake)
 
+if(TARGET ${${PROJECT_NAME}_PROTO_GENERATOR_PLUGIN})
+  set(${PROJECT_NAME}_PROTO_GENERATOR_PLUGIN_FILE $<TARGET_FILE:${${PROJECT_NAME}_PROTO_GENERATOR_PLUGIN}>)
+else()
+  set(${PROJECT_NAME}_PROTO_GENERATOR_PLUGIN_FILE ${${PROJECT_NAME}_PROTO_GENERATOR_PLUGIN})
+endif()
+
 gz_msgs_generate_messages_impl(
   MSGS_GEN_SCRIPT
     ${PROJECT_SOURCE_DIR}/tools/gz_msgs_generate.py
   FACTORY_GEN_SCRIPT
     ${PROJECT_SOURCE_DIR}/tools/gz_msgs_generate_factory.py
+  PYTHON_INTERPRETER
+    ${${PROJECT_NAME}_PYTHON_INTERPRETER}
+  PROTOC_EXEC
+    ${${PROJECT_NAME}_PROTOC_EXECUTABLE}
   GZ_PROTOC_PLUGIN
-    $<TARGET_FILE:${PROJECT_NAME}_protoc_plugin>
+    ${${PROJECT_NAME}_PROTO_GENERATOR_PLUGIN_FILE}
   INPUT_PROTOS
     ${proto_files}
   DLLEXPORT_DECL
@@ -54,6 +64,7 @@ gz_msgs_generate_messages_impl(
 )
 
 gz_msgs_generate_desc_impl(
+  PROTOC_EXEC ${${PROJECT_NAME}_PROTOC_EXECUTABLE}
   INPUT_PROTOS ${proto_files}
   PROTO_PATH ${PROJECT_SOURCE_DIR}/proto
   DEPENDENCY_DESCRIPTIONS ${depends_msgs_desc}

@@ -28,7 +28,16 @@ set(PROTO_SCRIPT_NAME "@PROJECT_NAME@_generate.py")
 set(FACTORY_SCRIPT_NAME "@PROJECT_NAME@_generate_factory.py")
 
 set(@PROJECT_NAME@_PROTO_PATH ${@PROJECT_NAME@_INSTALL_PATH}/share/protos)
-set(@PROJECT_NAME@_PROTO_GENERATOR_PLUGIN ${@PROJECT_NAME@_INSTALL_PATH}/bin/${PROTOC_NAME})
+# Provide support to override generator executable used during cross-compilation
+if(NOT DEFINED @PROJECT_NAME@_PROTO_GENERATOR_PLUGIN)
+  set(@PROJECT_NAME@_PROTO_GENERATOR_PLUGIN ${@PROJECT_NAME@_INSTALL_PATH}/bin/${PROTOC_NAME})
+endif()
+if(NOT DEFINED @PROJECT_NAME@_PROTOC_EXECUTABLE)
+  set(@PROJECT_NAME@_PROTOC_EXECUTABLE protobuf::protoc)
+endif()
+if(NOT DEFINED @PROJECT_NAME@_PYTHON_INTERPRETER)
+  set(@PROJECT_NAME@_PYTHON_INTERPRETER Python3::Interpreter)
+endif() 
 set(@PROJECT_NAME@_PROTO_GENERATOR_SCRIPT ${@PROJECT_NAME@_INSTALL_PATH}/bin/${PROTO_SCRIPT_NAME})
 set(@PROJECT_NAME@_FACTORY_GENERATOR_SCRIPT ${@PROJECT_NAME@_INSTALL_PATH}/bin/${FACTORY_SCRIPT_NAME})
 
@@ -64,6 +73,10 @@ function(gz_msgs_generate_messages)
 
   cmake_parse_arguments(generate_messages "${options}" "${oneValueArgs}" "${multiValueArgs}" ${ARGN})
   gz_msgs_generate_messages_lib(
+    PYTHON_INTERPRETER
+      ${@PROJECT_NAME@_PYTHON_INTERPRETER}
+    PROTOC_EXEC
+      ${@PROJECT_NAME@_PROTOC_EXECUTABLE}
     MSGS_GEN_SCRIPT
       ${@PROJECT_NAME@_PROTO_GENERATOR_SCRIPT}
     FACTORY_GEN_SCRIPT