Single compilation units

.. _single_compile_unit:

Even before reading [1]_, we noticed a great speed up in compile time for all PCL libraries if instead of compiling N object files and linking them together, we compile only one, and include all the sources of the N files in this main source. If you peek at an older version of PCL, you might notice things along the lines of:

.. code-block:: cpp :linenos:

// Include the implementations instead of compiling them separately to speed up compile time
#include "extract_indices.cpp"
#include "passthrough.cpp"
#include "project_inliers.cpp"
#include "statistical_outlier_removal.cpp"
#include "voxel_grid.cpp"

and in CMakeLists.txt:

.. code-block:: cmake :linenos:

rosbuild_add_library (pcl_ros_filters
                      src/pcl_ros/filters/filter.cpp
                      # Compilation is much faster if we include all the following CPP files in filters.cpp
                      #src/pcl_ros/filters/passthrough.cpp
                      #src/pcl_ros/filters/project_inliers.cpp
                      #src/pcl_ros/filters/extract_indices.cpp
                      #src/pcl_ros/filters/statistical_outlier_removal.cpp
                      #src/pcl_ros/filters/voxel_grid.cpp
                     )

For more information on how/why this works, see [1]_.

.. [1] http://gamesfromwithin.com/physical-structure-and-c-part-2-build-times