Implement ament_add_default_options (#390)

ament_cmake_core/cmake/core/all.cmake

@@ -39,6 +39,7 @@ endif()
 
 # various functions / macros
 foreach(filename
+  "ament_add_default_options"
   "ament_execute_extensions"
   "ament_package"
   "ament_package_xml"

ament_cmake_core/cmake/core/ament_add_default_options.cmake

@@ -0,0 +1,46 @@
+# Copyright 2022 Open Source Robotics Foundation, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+#
+# Explicit call to add default CMake options (e.g. BUILD_SHARED_LIBS)
+#
+# .. note:: It can be called multiple times, but should be called
+#   once for any package that requires the options.
+#
+# :param EXCLUDE_BUILD_SHARED_LIBS: Exclude the BUILD_SHARED_LIBS option
+#
+# @public
+#
+macro(ament_add_default_options)
+  # TODO(methylDragon): Would be good to parse args to skip options next time.
+  set(aado_options EXCLUDE_BUILD_SHARED_LIBS)
+  set(aado_oneValueArgs)
+  set(aado_multiValueArgs)
+  cmake_parse_arguments(ament_add_default_options
+    "${aado_options}" "${aado_oneValueArgs}" "${aado_multiValueArgs}" ${ARGN}
+  )
+
+  if(NOT ament_add_default_options_EXCLUDE_BUILD_SHARED_LIBS)
+    option(
+      BUILD_SHARED_LIBS
+      "Global flag to cause add_library() to create shared libraries if on. \
+       If set to true, this will cause all libraries to be built shared \
+       unless the library was explicitly added as a static library."
+      ON)
+  endif()
+
+  unset(aado_options)
+  unset(aado_oneValueArgs)
+  unset(aado_multiValueArgs)
+endmacro()